Histone III is a substrate for in vitro phosphorylation by a catalytic fragment of protein kinase C. Protein kinase C-catalyzed phosphorylation of histone III was induced by 50 nM phorbol-12-myristate-13-acetate (PMA), and inhibited by protein fractions and the ginsenosides-$Rb_1$, $-Rg_1$, and $-Rh_2$ from Panax ginseng CA. Meyer. The protein fraction which was extracted with methanol consisted mainly of glycopeptides with molecular weights below 18 KDa. The protein fraction extracted with acetone consisted of 18 KDa polypeptides. Protein fractions and ginsenosides from Panax ginseng CA. Meyer have antitumor effects since the inhibition of protein kinase C is related to the suppression of tumors.