MAPK8 and cyclic hematopoiesis: Although molecular pathways of cavernosal apoptosis induced by CN injuries are still poorly understood, several previous studies, including a previous study of ours, have reported that a few apoptotic pathways including Sonic hedgehog, Rho-kinase, and JNK pathways, are involved in cavernosal apoptosis following CN injury [24,25,26,27].