RARA and acute myeloid leukemia: In agreement with our hypothesis, ATRA causes autophagy in differentiating AML cells.9, 10, 11, 12 Additionally, NB4-resistant cells (NB4-R2), which are unable to differentiate upon ATRA administration, do not show an autophagic response to retinoids.11 A study by Anguiano et al.24 demonstrated that ATRA does not promote macroautophagy in mouse fibroblasts, although RARα knockdown decreased macroautophagy under basal conditions in these terminally differentiated cells.