Mouse myeloma. A model for studies of cell kinetics

The mouse plasma cell tumor Adj PC-5 grows slowly due to a large loss of cells from the growth fraction into nonprolifeative, end-stage cells. All tumor cells with the capacity to form a colony appear to be in cell cycle. Marked tumor specificity of several alkylating agents could not be explaned by differences in the porliferative state of myeloma and normal marrow cells. The sensitivity of different mouse myelomas to an alkylating agent varies considerably. The factors determining whether a mouse myeloma is sensitive to an alkylating agent are probably related to structure of the agent and intrinsic properties of the cell, rather than to the agent's mechanism of action.