MAPK8 and familial pancreatic carcinoma: A known consequence of ROS accumulation in pancreatic cancer cells is activating phosphorylation of c-Jun N-terminal kinase (JNK), which causes cell cycle arrest at G2/M and subsequently apoptosis.11 Cyst(e)inase treatment caused activation of JNK within 1 h of treatment in Panc1 cells, but not in the other two more resistant cell lines (Fig. 1f).