SK053 is a potent anti-leukemic agent that induces differentiation of human AML cells. (A) Cytostatic/cytotoxic activity of SK053 in human AML cell lines evaluated with trypan blue staining, mean percentage of dead cells ± SD, n=6; *P<0.05 vs controls, one-way ANOVA with Dunett’s post test; (B) SK053 inhibits enzymatic activity of recombinant human PDI in a turbidimetric assay of insulin disulfide reduction; 130 µM bacitracin served as a positive control; (C) qPCR results presented as mean target-to-reference ratio ± SD (left) CEBPA expression in HL60 cells incubated for indicated time with 10 µM SK053; (right) HK3 expression in HL60 cells incubated for 48 hours with 10 µM SK053, or 1 µM ATRA (positive control); (D) SK053 increases amount of CEBPA protein in nuclear fraction of HL60 cells incubated for 2 or 5 days with 1 µM ATRA (positive control), 2 mM bacitracin (PDI inhibitor) or 10 µM SK053; the figure presents results of Western blot, HDAC2 served as a marker of nuclear fraction, ß-actin served as a loading control.