TheeffectofTPA,apotenttumorpromoter,onSSV-NIH3T3cellsinserum-freemediumwasinvestigated.TPAstimulatedDNAsynthesisofSSV-NIH3T3cellsonthethirddayofcultureinSFM.InSDS-PAGFofmediumconditionedbyTPA-treatedSSV-NIH3T3cells(inSFM+TPA),theamountsoffourproteinsof31.0Kd,28.5Kd,25.5Kdand13.5Kdstrikinglyincreasedoverthatofnon-TPA-treatedcounterpart(inSFM).ThePDGF-likeactivitywasalsodetectedinCMofSFM+TPA.WheninsulinandEGFweredrownofftheSFM+TPA(SFM-Ins-EGF+TPA),TPAlostitsabilitytostimulateDNAsynthesisofSSV-NIH3T3cellsonthethirddayandSDS-PAGEoftheconditionedmediumshowedthattheamountsofthefourproteinsnotedabovegratelyreduced.However,cellsinSFM-Ins-EGF+TPAwereinalmostthesamegrowthconditionascellsincompleteSFM+TPAonthethirddayofculture.Resultswerediscussedinthepaper.
