In extracellular secreted form, promotes proliferation and activation of CD8(+) T cells, suggesting a cytokine-like function (PubMed:25125657). Enhances cytotoxic anti-tumor activity of CD8(+) T cells (PubMed:25125657). May inhibit ERK and JNK signaling activity (PubMed:18087676, PubMed:23070808). May suppress cell migration and invasion activity, via its effects on ERK and JNK signaling (PubMed:23070808). In the nucleus, enhances stability of the PCAF histone acetyltransferase (HAT) complex member TADA2A and thus promotes PCAF-mediated H3K14 and H4K8 HAT activity. May inhibit TADA2A-mediated TP53/p53 'Lys-321' acetylation, leading to reduced TP53 stability and transcriptional activity. May also promote TADA2A-mediated XRCC6 acetylation thus facilitating cell apoptosis in response to DNA damage. Interacts with TADA2A. Associates with the PCAF complex via TADA2A binding. Accumulates in the nucleus in response to UV irradiation (PubMed:22644376). Expressed in cervical gland, cervical squamous epithelium, endometrium, stomach, kidney distal convoluted tubule, spermatogenic cells in testis, mammary gland, liver and striated muscle (at protein level) (PubMed:18087676, PubMed:23070808). Also detected in placenta (PubMed:18087676). Highest expression in testis relative to other tissues (PubMed:18087676). Detected in T cells and dendritic cells; highly expressed in activated CD8(+) T cells, and also expressed at lower levels in CD4(+) T cells (PubMed:25125657). O-glycosylated, with additional sialic acid modifications. Belongs to the CCDC134 family.