Inhibition of ATRA metabolism leads to high growth of NB4-resistant subclones. Percentage of resistant NB4 subclone growth following treatment with either ATRA (A) or RAMBA (B). Statistical analysis was performed on 100 clones for each condition. (C) RAMBA-treated subclones showing growth were confirmed to be resistant to ATRA using the NBt test. Error bars represent the standard error (n = 7). (D) Western blot revealing the presence of the PML/RARα protein in 3 RAMBA-treated resistant clones.