CD437-enhanced GADD 45 mRNA expression. 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 a laser densitometer and values were normalized with respect to 18S mRNA signals. (A) A representative Northern blot assay from two separate determinations. (B) Quantification of a representative experiment.