Retinoic acid (RA; active metabolite of vitamin A) plays a prominent role in regulating the transition of proliferating precursor cells (such as carcinoma cells and neuronal precursors) to postmitotic differentiated cells. The retinoid , Xenopus/Amphibian, receptors (R, Xenopus/Amphibian,Rs) family (R, Xenopus/Amphibian,R?, (B) and ?),Porcinereferentially bind 9-cis-RA and regulate gene transcription by forming heterodimers with a second family of RA receptors. RAs have been suggested to potentially play a therapeutic role in cervical cancer. RAs are known to play key roles in neuronal development and an increasing body of evidence indicates that retinoid signaling may regulate synaptic plasticity and associated learning and memory behaviors.