RARA and acute promyelocytic leukemia: X-RARα fusion proteins in APL have been demonstrated to negatively affect transactivation of PPARγ [74], indicating that inhibition of PPARγ activity may contribute to the pathophysiology of the differentiation block in APL, and that PPARγ ligands could sensitize APL cells to the differentiating effects of ATRA including ATRA-resistant cells [45].