ATRA and ATO induce autophagy-dependent degradation of PML/RARA. (A) NB4 cells treated with ATRA (1μM) or ATO (1μM) alone or in combination for 24 hours were subjected to SDS-PAGE followed by immunoblotting with anti-RARA, anti-LC3, and antitubulin antibodies. (B) Quantification of the data shown in panel A. Relative protein levels are presented as mean ± SEM from 3 independent experiments. *P < .05, Student t test. (C) Western blot analysis of PML/RARA in NB4 cells treated with the drugs indicated. Incubation of cells in the presence of ATRA (1μM) or ATO (1μM) was performed for 24 hours. Baf A (100nM) was present during the last 12 hours of the incubation. (D) Quantification of the data shown in panel C. Relative PML/RARA protein levels are presented as mean ± SEM from 3 independent experiments.