CCND1 and papilloma: NAC has been shown to inhibit 12-O-tetradecanoylphorbol-13-acetate (TPA)-mediated induction of cyclin D1 and DNA synthesis [71], to diminish DNA synthesis in human astrocytoma cells [72], to inhibit p38 mitogen-activated protein kinase (MAPK) activation and abnormal cell cycle progression in human lymphoma cells [73], and to induce CDK inhibitors and G1 cell cycle arrest in murine papilloma cells [74].