MAPK14 and neoplasm: This system is also involved in regulating p38 activity [11], [41]–[43] and there is evidence that direct PKA-dependent phosphorylation of RhoA at Ser 188 inhibits its activity in endothelial cells [44], in smooth muscle cells [45], in cytotoxic lymphocytes [46] and in tumor cells [11] suggesting that PKA and RhoA could regulate p38 activity through a common pathway.