AICDA and cancer: We then proposed that due to the potential danger of AID/APOBEC activity for genomic DNA, this inherent structural regulatory mechanism is in place as a safe-guard mechanism in AID and in the tumorigenic A3 family members; the main pillar of this hypothesis was that the open:closed dynamic ratio in AID, A3A and A3B correlated with their catalytic rates and with their relative responsibility for mediating tumorigenic mutations in cancers.