Anchorage independence: Analysis of factors affecting the growth and colony formation of wild-type and dl [formula omitted] mutant SV40-transformed lines

Abstract

We have studied in detail the parameters of anchorage-independent growth of normal rat cells and two clones of simian virus 40 (SV40)-transformed rat fibroblasts. Normal secondary rat embryo fibroblasts (REF) suspended in soft agar neither form large colonies (greater than 0.2-mm in diameter) nor show any appreciable increase in total cell volume. A clone of wild-type SV40-transformed REF grows in agar with a colony-forming efficiency of 54% and an increase in total cell volume greater than 10 3. A clone of REF transformed by the SV40 early deletion mutant 884 has a colony-forming efficiency in agar of only 0.02%, but the total increase in cell volume is greater than 100-fold. In defining anchorage transformants, a distinction must be made between the ability to form large colonies and the ability to undergo a significant number of doublings. Transformation by the viable deletion mutant 884 apparently is impaired far more in the former aspect than in the latter.