Retinoic acid, in the form of ATRA, is used with great success in the clinical setting for a subset of acute promyelocytic leukemia patients who have chromosomal translocations involving the retinoic acid receptor-α gene, RARα[47], but the use of retinoids in solid tumors has not been promising to date [48]. This evidence concerns the gene RARA and acute promyelocytic leukemia.