Real-time quantitative PCR analysis of HOXgene expression in NB4 cells treated with ATRA.

Complementary DNAs obtained from NB4 cells were analyzed forHOX gene expression using the SMART-HOX platform. The data graphically presented are the cycle threshold (C_T) values of the particular HOX gene normalized to the endogenous 18SrRNA control. All data points are the mean of 3 independent experiments plus standard errors for the particularHOX genes following (A) short-term ATRA exposure (░, 4-hour EtOH; ▪, 4-hour ATRA) or (B) the onset of differentiation after ATRA exposure (░, 48-hour EtOH; ▪, 48-hour ATRA). The C_T value is inversely proportional to the gene expression. The most significant changes in HOX gene expression following ATRA treatment are plotted (C) as relative fold differences in the means of 3 experiments over the appropriate vehicle control, where fold difference = 2^ΔCT and ΔC_T= C_T (EtOH) − C_T (ATRA). In the cases where ΔC_T was a negative integer, the fold difference was calculated as − 2^ΔCT. ░ indicates 4-hour ATRA; and ▪, 48-hour ATRA.