The presence of both growth inhibitory and growth stimulatory factors on membranes prepared from mouse liver.

Plasma membrane fractions from mouse livers were examined for the presence of growth regulatory peptides. Both growth inhibitory and growth stimulatory factors were found on these membranes. The growth inhibitory component could be enriched by extractions with both dimethylmaleic anhydride and octylglucoside. The growth stimulatory component could be removed from the membrane by either freeze-thaw, high salt, protease or pyrophosphate treatment, indicating that this factor is an extrinsic membrane protein. The existence of these factors on liver membranes provides an easily obtainable source for the large-scale purification of these molecules and may indicate a possible role in normal tissue growth.