MAPK3 and hepatocellular carcinoma: GRB2 immunoreactivity showed complementary expression dynamics, with ANT tissues exhibiting negative staining and HCC samples displaying robust cytoplasmic staining characterized by diffuse granular deposition in the perinuclear region (Fig. 4D, Supplementary Fig. 2C), and ERK1/2 exhibited the same effect (Fig. 4E, Supplementary Fig. 2D).