Some factors influencing the behavior of BHK 21 Cl 13 cells in soft agar medium

As part of an attempt to reproduce Styles' cell transformation assay, the effect of serum concentration on the growth of normal and 4-nitroquinoline-1-oxide (4-NQO)-treated BHK 21 Cl 13 cells in soft agar medium was examined. Using medium with 10% newborn calf serum, dilution of control cultures from 5 x 10(4) to 1.56 x 10(3) cells/ml caused little increase in the number of countable (greater than 0.3 mm diameter) colonies, but 4NQO caused a marked dose-related increase. In contrast, using 20% of the same batch of serum, 4NQO-treated groups and controls diluted to comparable viability counts showed very similar increases in countable colonies. Clones greater than 0.3 mm diameter isolated from control cultures with 20% serum did not appear to be transformed when grown in agar with 10% serum. These data indicate that factors other than neoplastic transformation can influence the growth of BHK 21 Cl 13 cells in soft agar medium.