RARS1 and neoplasm: The biological effects of AtRA are mainly mediated by two families of nuclear retinoic acid receptors (RARs), each consisting of three receptor subtypes designated by α, β, and γ: the RARs and the retinoid X receptors (RXRs) that are expressed in lymphoid cells and act as transcription factors to regulate cell signaling, differentiation, and tumor suppression [85].