Specific knockdown of HAP1 confers l-asparaginase resistance. (A) Depletion of HAP1 mRNA (left) and protein (right) in cells infected with retrovirus carrying pRS-shHAP1 #1. Representative data (upper) from 1 of 3 independent experiments showing similar result patterns are shown. Bottom panels show the ratios of HAP1 levels vs GAPDH (for mRNA) or actin (for protein) levels from densitometric analysis of gel/blot images. Standard deviation for the 3 independent sets of experiments was calculated based on the ratios of the levels of HAP1 vs GAPDH (for mRNA) or vs actin (for protein) that were, in turn, based on densitometry of gels/blots using National Institutes of Health Image J 1.61 with the GAPDH and actin values, respectively, normalized to 1.0. (B) Infection of parental SEM leukemic cells (*) with retrovirus carrying pRS-shHAP1 #1 confers l-asparaginase resistance. Cells were treated with l-asparaginase for 4 days and surviving fractions were quantified using Alamar blue assay. Values are means ± standard error of the mean from 3 independent experiments.