CD437-enhanced p21^WAF1/CIP1 mRNA expression in HL-60R cells. Exponentially growing HL-60R cells were exposed to 1 μmol/L CD437 for varying periods of time. Cells were harvested and Northern blots were performed as described in the Materials and Methods. The intensity of each band was scanned using laser densitometry and values were normalized with respect to 18S mRNA signals. (A) A representative Northern blot from two separate determinations. (B) Quantification of a representative experiment.