<prompt> Isotretinoin is:All trans retinoic acidAll cis retinoic acid13 trans retinoic acid13 cis retinoic acid  <response>: Isotretinoin is a synthetic retinoid i.e. 13 cis retinoic acid uses:- Acne vulgaris Oral leukoplakia Pityriasis rubra pilaris Side effects:- Alopecia Tendon rupturetendinitis Elevation of Lipoprotein a Teratogenicity. All-trans retinoic acid is involved in cell differentiation. All-trans retinoic acid binds to nuclear receptors retinoic acid receptors. The activated retinoic acid-receptor complex interacts with response elements on the DNA and regulates the transcription of specific genes in different tissues. Ex: Control of expression of keratin gene in epithelial tissues. NOTE: All-trans retinoic acid ATRA is used in the treatment of acute promyelocytic leukemia. 