Effect of insulin-dependent cytoplasmic regulator on murine melanoma KML cell proliferation

Insulin-dependent cytoplasmic regulator (IDR), the activity of which correl ates with the insulin level in blood, was isolated from rat liver and fract ionated on a Sephadex G-25 column. Radioautography established that IDR sti mulates by 30% proliferation of murine melanoma KML cells in culture. This is indicated by H-3-thymidine incorporation into the cell nucleus. It is pr oposed that insulin stimulates proliferation of the melanoma KML cell cultu res through an intercellular intermediate, IDR.