Mitogenic proteins of the 3T3 plasma membrane

A mitogenic factor from 3T3 plasma membranes has been identified and partially characterized. The factor appears to be a peripheral membrane protein that can be released by mild trypsin, chymotrypsin, or plasmin treatment. This component is sensitive to heat and acid, and has a molecular weight in the range of 150,000-200,000 daltons as determined by gel filtration. A similar mitogenic activity has also been found on the membranes of both SV-40-transformed 3T3 cells and human fibroblasts. The factor appears to be distinct from all previously described mitogenic components.