Combined effect of ATRA and TSA on differentiation of the ATRA-resistant NB4-MRA1 APL cells.

(A) Expression of the differentiation marker CD11b by flow cytometry analysis. NB4, NB4-MRA1, and UF-1 APL cells were treated with 25 nM TSA, 1 μM ATRA, and the combination for 3 days. Numbers in parentheses indicate mean channel fluorescence. This experiment is representative of 3 that gave comparable results. (B) NBT reduction analysis of NB4, NB4-MRA1, and UF-1 APL cells treated with the indicated concentrations of agents for 5 days. Each data point represents the mean of 3 independent experiments, and bars denote SD.