Phorbol esters and vasopressin stimulate DNA synthesis by a common mechanism.

The potent tumour promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) acts synergistically with all known mitogens to induce DNA synthesis in 3T3 cells. In contrast, the neurohypophyseal hormone vasopressin, which is mitogenic for 3T3 cells, fails to synergize with TPA to stimulate DNA synthesis, ornithine decarboxylase activity or 2-deoxyglucose uptake. Thus TPA acts through a pathway which converges with that used by vasopressin, and at least some of its biological effects occur through mechanisms normally utilized by specific hormones.