Guanine nucleotide-binding proteins (G proteins) are involved as modulators or transducers in various transmembrane signaling systems (PubMed:19151758, PubMed:21212405, PubMed:22609986). Activates effector molecule RhoA by binding and activating RhoGEFs (ARHGEF12/LARG) (By similarity). GNA12-dependent Rho signaling subsequently regulates transcription factor AP-1 (activating protein-1) (PubMed:19151758, PubMed:21212405). GNA12-dependent Rho signaling also regulates protein phosphatese 2A activation causing dephosphorylation of its target proteins (By similarity). Promotes tumor cell invasion and metastasis by activating RhoA/ROCK signaling pathway and up-regulating pro-inflammatory cytokine production (By similarity). Inhibits CDH1-mediated cell adhesion in process independent from Rho activation (By similarity). Together with NAPA promotes CDH5 localization to plasma membrane (By similarity). May play a role in the control of cell migration through the TOR signaling cascade (PubMed:22609986). G proteins are composed of 3 units; alpha, beta and gamma (PubMed:16388592). The alpha chain contains the guanine nucleotide binding site (PubMed:16388592). Interacts with UBXD5 (By similarity). Interacts (in GTP-bound form) with PPP5C (via TPR repeats); activates PPP5C phosphatase activity and translocates PPP5C to the cell membrane (By similarity). Interacts with RGS22 (By similarity). Interacts (via N-terminus) with NAPA; the interaction promotes CDH5 localization to plasma membrane (By similarity). Interacts with CTNND1 (via N-terminus); the interaction regulates CDH1-mediated cell-cell adhesion (PubMed:15240885). Interacts with PPP2R1A; the interaction promotes protein phosphatase 2A activation causing dephosphorylation of MAPT (By similarity). Interacts (in GTP-bound form) with ARHGEF1 (PubMed:16388592). Interacts (in GTP-bound form) with ARHGEF11 (via RGS domain) (By similarity). Interacts (in GTP-bound form) with ARHGEF12 (via RGS domain) (PubMed:16388592). CDH1 enhances cell membrane localization. Myristoylation of mutated N-terminus in place of original palmitoylation restores the transformation activity. Belongs to the G-alpha family. G(12) subfamily.