The effect of anti-Ig on gene expression was relatively specific since the level of total (shown by Northern blots) and cytoplasmic (dot blots) mRNA of several other genes (beta-actin, G6PD, kappa-L chain) and the first exon of c-myc (in cell lines in which this exon is expressed separately from the second and third exons) was not changed in these same BL cell lines.