Marked alteration in phosphorylation of the RB protein during differentiation of human promyelocytic HL60 cells.
The phosphorylation state of the RB protein was found to change markedly during cell differentiation: most of the RB protein was in a highly phosphorylated 115 kD form in human promyelocytic HL60, erythroleukemic K562 and monocytic U937 cells, but during tumor promoter-induced differentiation, the amount of this form decreased and the amount of an under-phosphorylated 110 kD form of the RB protein increased. Induction of differentiation of HL60 cells by dimethylsulfoxide also induced a similar alteration of the RB protein. However, no alteration in the ratio of the two forms was observed in cell lines such as epidermoid carcinoma A431 and adenocarcinoma MKN-7 that were not induced to differentiate by tumor promoter treatment. The highly phosphorylated form and under-phosphorylated form exhibited different affinity for DNA-cellulose and SV40 large T antigen.
Akiyama
T
T
Department of Oncology, University of Tokyo, Japan.
Toyoshima
K
K
D000952:Antigens, Polyomavirus Transforming / Q000378:metabolism; D002454:Cell Differentiation; D006801:Humans; D015473:Leukemia, Promyelocytic, Acute / Q000378:metabolism* / Q000473:pathology; D009363:Neoplasm Proteins / Q000378:metabolism*; D010766:Phosphorylation; D012175:Retinoblastoma / Q000235:genetics*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D000952:Antigens, Polyomavirus Transforming; D009363:Neoplasm Proteins; D013755:Tetradecanoylphorbol Acetate