• 1 January 1981
    • journal article
    • research article
    • Vol. 41  (1) , 306-309
Abstract
A flow cytometric study was carried out on the effects of tumor-promoting 12-O-tetradecanoylphorbol-13-acetate (TPA; 10-8 M) on HeLa [human cervical carcinoma] cells synchronized by amethopterin for DNA synthesis. Cells treated with TPA at the time of release from the amethopterin block showed a delayed passage through S phase and partially through G2 in their immediate life span as measured 24 h after release. This late G2 delay was not observed when TPA was added to cells during late S or G2 phase. A direct inhibition of cells in G2 became evident as observed .apprx. 15 h after release from block. None of these effects was caused by the nonpromoting 4-O-methyl-12-O-tetradecanoylphorbol-13-acetate (10-6 M). These data support observations obtained with asynchronous cultures. The TPA effects resemble those reported after X-irradiation of cell cultures.