Acts as an inhibitor of the small GTPase RHOA and plays several roles in the regulation of myoblast and hair cell differentiation, lymphocyte T proliferation and neutrophil polarization (PubMed:17150207, PubMed:24687993, PubMed:23241886, PubMed:24958875, PubMed:25588844, PubMed:27556504). Inhibits chemokine-induced T lymphocyte responses, such as cell adhesion, polarization and migration (PubMed:23241886). Involved also in the regulation of neutrophil polarization, chemotaxis and adhesion (By similarity). Required for normal development of inner and outer hair cell stereocilia within the cochlea of the inner ear (By similarity). Plays a role for maintaining the structural organization of the basal domain of stereocilia (By similarity). Involved in mechanosensory hair cell function (By similarity). Required for normal hearing (PubMed:24958875). Acts as an inhibitor of the small GTPase RHOA (PubMed:25588844). Plays a role in fetal mononuclear myoblast differentiation by promoting filopodia and myotube formation (PubMed:17150207). Maintains naive T lymphocytes in a quiescent state (PubMed:27556504). Homooligomer; homooligomerization is regulated by RHOC and leads to the formation of concatemers through the association of N- and C-termini (By similarity). Interacts with 14-3-3 proteins; these interactions occur during myogenic cell differentiation (PubMed:24687993). Interacts with HDAC6; this interaction occurs during early myogenic differentiation and prevents HDAC6 to deacetylate tubulin (PubMed:24687993). Interacts with DYSF; this interaction occurs during early myogenic differentiation (PubMed:24687993). Interacts with MYOF (PubMed:24687993). Interacts with RHOC (By similarity). Isoform 1 and isoform 2 interact (via active GTP- or inactive GDP-bound forms) with RHOA; these interactions are direct, block the loading of GTP to RHOA and decrease upon chemokine CCL19 stimulation in primary T lymphocytes (PubMed:23241886, PubMed:25588844). Isoform 2 interacts (phosphorylated form) with HDAC6; this interaction induces T cell proliferation arrest (PubMed:27556504). Isoform 2 interacts (phosphorylated form) with 14-3-3 proteins; these interactions induces T cell proliferation arrest (PubMed:27556504). Isoform 2 interacts with 14-3-3 proteins (PubMed:25588844). Isoform 2 interacts (via phosphorylated form) with YWHAB; this interaction occurs in a chemokine-dependent manner and does not compete for binding of RIPOR2 with RHOA nor blocks inhibition of RIPOR2-mediated RHOA activity (PubMed:25588844). Isoform 2 interacts with YWHAE (PubMed:25588844). Isoform 2 interacts with YWHAQ (PubMed:25588844). Localized in the cytoplasm in cells undergoing mitosis (PubMed:17150207). Colocalized with F-actin (PubMed:17150207). Localized with RHOC within the basal domain of hair cell stereocilia, near the taper region (By similarity). Detected in punctate pattern forming a circumferential ring at the stereocilia base (By similarity). Localized to the apical stereocilia of inner and outer hair cells (By similarity). Not detected as a membrane-associated protein in stereocilia (By similarity). Accumulates at the leading edge of polarized neutrophils in a chemokine-dependent manner (PubMed:25588844). Expressed in primary fetal mononuclear myoblast (PubMed:17150207). Expressed strongly in naive T lymphocytes (PubMed:27556504). Expressed weakly in activated T lymphocytes (at protein level) (PubMed:27556504). Expressed in blood cells and adult tissues of hematopoietic origin, such as the secondary lymphoid organs (PubMed:23241886). Expressed in cytotrophoblast (PubMed:9055809). Up-regulated during fetal mononuclear myoblast differentiation (PubMed:17150207, PubMed:24687993). Up-regulated during cytotrophoblast differentiation (PubMed:9055809). Up-regulated during granulocyte differentiation (PubMed:9055809). Isoform 1 and isoform 2 are down-regulated in T lymphocytes upon T-cell antigen receptor (TCR) stimulation (PubMed:27556504). Isoform 1 and isoform 2 are up-regulated by FOXO1 (PubMed:23241886). Phosphorylated. Isoform 2 is phosphorylated in T cells (PubMed:27556504). Chemokine-induced phosphorylation of isoform 2 in neutrophils occurs in a PKC- and AKT-dependent manner, resulting in RIPOR2 interaction with YWHAB and stabilization (PubMed:25588844). Isoform 2 is phosphorylated by PKCA, AKT1 and MAPKAPK1A; in vitro (PubMed:25588844). Acetylated during myogenic differentiation. The disease is caused by variants affecting the gene represented in this entry. Cells lacking isoform 2 exhibit a severe reduction of myotube formation. In contrast, isoform 2 overexpression induces formation of filopodia. Belongs to the RIPOR family. Extended N-terminus.