MAPK3 and gallbladder carcinoma: Tyrosine-phosphorylated FRS2 is allowed to bind to growth factor-bound protein 2 (GRB2) to activate downstream signaling cascades to induce phosphorylation of ERK1/2 [155,156,157], after which phosphorylated ERK1/2 promotes mitogenesis of hepatocytes to regenerate liver tissue under physiological conditions [158,159,160] and progress hepatocarcinoma [128,161,162], neck squamous cell carcinoma [163], and gallbladder carcinoma cells [164] under pathogenic conditions.