RARA and acute lymphoblastic leukemia: In our study, ATRA appears to utilize RXR, and not RAR, to affect the number of viable BCR-ABL ALL cells because RARα, RARβ and RARγ specific agonists all failed to decrease the number of viable leukemic cells, while ATRA, 9-cis-RA, the RXR pan-agonist bexarotene and the RXRα specific agonist potently and efficaciously decreased the number of viable BCR-ABL ALL cells (Fig. 7D–F).