Hematopoiesis in long-term bone marrow cultures treated with MMS350. Long-term bone marrow cultures were established according to the materials and methods section. Non-adherent cells were harvested weekly. Prior to non-adherent cell harvest, the adherent layer was assayed for percent of the surface area of the flask that was confluent (A). The cobblestone islands were scored and indicate hematopoietic stem cells in the adherent layer (B), cumulative cobblestone islands (C), non-adherent cells removed weekly per flask (D), and cumulative non-adherent cells per flask, (E) were determined. Non-adherent cells were then assayed for hematopoietic colony forming cells. Non-adherent cells were plated in secondary semi-solid medium and colony-forming cells of greater than 50 cells per colony were scored weekly on day 7 (F), and cumulative (G). Plates were again scored for those forming colonies at day 14 weekly (H) and cumulative (I). Statistics are shown in Tables I–V.