PML/RARA is degraded by autophagy. (A) Immunoblot (IB) showing optimal extraction efficiency of PML/RARA by a buffer containing UREA. NB4 cells were first solubilized in a lysis buffer containing Triton X-100. The pelleted material was further dissolved in either SDS containing or UREA containing buffers. (B) NB4 cells grown in nutrient-rich medium were treated or not with Baf A (100nM) for 12 hours or with 3-MA (10mM) for 4 hours, or cells were incubated in starvation media (EBSS) for 4 hours, followed by IB with anti-RARA, anti-p62, or anti-tubulin antibodies. The band corresponding to PML/RARA (110 kDa) is shown. The whole blot, including RARA (50 kDa), is shown in supplemental Figure 2. (C) Quantification of relative protein level from 3 independent experiments. Data are mean ± SEM. *P < .05, Student t test.