FIGURE 2.
Defective induction after irradiation exposure and reduced basal expression of p21 WAF1 protein and mRNA in ALL cell lines and primary cells. ALL cell lines (a and b) or primary cells (c and d) were irradiated (IR) (3.5 cGy), and 6 h later expression of p53 or p21WAF1 proteins (a and c) and mRNA (b and d) were assessed by immunoblot or RT-qPCR, respectively. a and c, a representative blot is shown from at least three independent experiments. c and d, primary T-ALL samples are suffixed with T and bone marrow relapse lysates suffixed with r. b and d, p21WAF1 mRNA expression was normalized to actin and expressed relative to p21WAF1 expression in the untreated TK6 cell line. Results represent the mean ± S.E. of three independent measurements. An asterisk represents a value significantly greater than control (C) (p < 0.05) as determined by paired t test, on log transformed data to equalize variance; ns, not significant. e, expression of p21WAF1 mRNA in primary ALL samples was analyzed by RT-qPCR and normalized to the corresponding EF-1α sample, and values were expressed as fold differences relative to p21WAF1 expression in Nalm-6 cells. f, p21WAF1 protein expression was assessed by immunoblot and normalized to TK6 control cells. In e and f, each symbol represents the mean expression of a primary sample calculated from three individual experiments. Differences between groups were compared using the Mann-Whitney U test. Bars represent the median.