MAPK3 and neoplasm: In the study conducted by Pao et al., increased expression of protein kinase C (PKC), extracellular signal-regulated kinase 1/2 (ERK1/2), and c-Jun N-terminal kinase (c-JNK) was observed in mouse Leydig tumor cells treated with COR signaling pathways, leading to cell death in the tumor cells (59).