Anti-IgM treatment down-regulates A-myb mRNA levels in WEHI 231 cells.

(A) WEHI 231 cells were treated with 2 μg/mL of anti-IgM antibody and total RNA was isolated from treated and untreated cells at the indicated time points. Samples (20 μg) were subjected to Northern blot analysis for RNA expression of c-myc (top panel) or A-myb (bottom panel). Equal loading was assessed by ethidium bromide staining of the gel (data not shown). (B) The resulting autoradiographs were subjected to densitometric scanning, and the values for signals of A-myb or c-myc are given as percentages relative to that observed in untreated cells (0 hour), arbitrarily set at 1. The exposure times were in the range of linearity as determined by multiple exposures.