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Retinoic acids can inhibit cell proliferation and promote cell differentiation, and have already been widely used in the treatment of many skin diseases, especially in that of abnormally proliferative dermatoses. Recently, retinoic acids have been introduced into the treatment of skin tumors. Herein the authors summarize the application of retinoic acids in the treatment of skin tumors and involved mechanisms, such as the promotion of apoptosis and suppression of proliferation of tumor cells via the activation of signaling molecules ��including activator protein-1 (AP-1), p73, tazarotene-induced gene 3 (TIG-3), signal transducers and activators of transcription 3 (Stat3)��and signaling pathways (e.g., B-Raf/Mek/Erk and Hedgehog).

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