PCNA and red-green color blindness: The balance between BCL‐2 proteins, mainly BCL‐X and MCL‐1, and BAX is believed to determine the death or survival of germ cells (Sun et al., 2017). Additionally, the activation of a p63/p53‐ and PCNA‐dependent checkpoint also plays a major role in eliminating defective oocytes during CBD and follicle formation (Klinger et al., 2015).