Guanine nucleotide-binding proteins (G proteins) are involved as modulators or transducers in various transmembrane signaling systems (PubMed:22609986, PubMed:15525651, PubMed:15240885, PubMed:17565996, PubMed:12515866, PubMed:16787920, PubMed:16705036, PubMed:23762476, PubMed:27084452). Activates effector molecule RhoA by binding and activating RhoGEFs (ARHGEF12/LARG) (PubMed:15240885, PubMed:12515866, PubMed:16202387). GNA12-dependent Rho signaling subsequently regulates transcription factor AP-1 (activating protein-1) (By similarity). GNA12-dependent Rho signaling also regulates protein phosphatese 2A activation causing dephosphorylation of its target proteins (PubMed:15525651, PubMed:17565996). Promotes tumor cell invasion and metastasis by activating RhoA/ROCK signaling pathway and up-regulating pro-inflammatory cytokine production (PubMed:23762476, PubMed:16787920, PubMed:16705036, PubMed:27084452). Inhibits CDH1-mediated cell adhesion in process independent from Rho activation (PubMed:11976333, PubMed:16787920). Together with NAPA promotes CDH5 localization to plasma membrane (PubMed:15980433). 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:10026210). The alpha chain contains the guanine nucleotide binding site (By similarity). Interacts with UBXD5 (PubMed:16202387). Interacts (in GTP-bound form) with PPP5C (via TPR repeats); activates PPP5C phosphatase activity and translocates PPP5C to the cell membrane. Interacts with RGS22 (PubMed:18703424). Interacts (via N-terminus) with NAPA; the interaction promotes CDH5 localization to plasma membrane (PubMed:15980433). 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 (PubMed:15525651). Interacts (in GTP-bound form) with ARHGEF1 (By similarity). Interacts (in GTP-bound form) with ARHGEF11 (via RGS domain) (PubMed:10026210). Interacts (in GTP-bound form) with ARHGEF12 (via RGS domain) (PubMed:11094164). CDH1 enhances cell membrane localization. Belongs to the G-alpha family. G(12) subfamily.