Anchorage-independent cell growth-inhibiting factor(s) from normal rat liver and ascites hepatoma

Acid/ethanol extracts of normal rat liver and rat ascites hepatoma cells (AH 130) were found to inhibit the epidermal growth factor (EGF)-dependent colony formation of Balb/c 3T3 cells. The extracts did not inhibit the growth of the 3T3 cells in monolayer culture. The inhibitory activities were heat- and acid-stable and were not inactivated by the treatment with pronase, RNase and DNase. Upon ultrafiltration, a considerable fraction of the inhibitory activities were found in the fraction corresponding to the molecular size ranging from 3.5 to 10 Kd, in which no appreciable TGF-beta activity was detected.