Autoradiographic analysis of the proliferation in vitro of six murine cell lines of non‐malignant or malignant origin

A high rate of cell growth in culture has often been thought to be indicative of malignancy. In the present work the generation time of six murine cell lines and the duration of their various mitotic and intermitotic phases were studied using thymidine‐6‐ 3 H and autoradiography. No definite correlation could be established between the growth kinetics and the tumor‐producing capacity of these cells, but cultures which were more than one year old showed a slightly shorter generation time and a somewhat shorter phase of DNA synthesis (ts) than 6‐ to 8‐month‐old cultures.