Regulation of cortactin expression by hematopoieticfactors in bone marrow. Bone marrow-derived cells were prepared and cultured for 4 days as described in the Materials and Methods. (A) Fresh bone marrow cells; (B) cells in 10% fetal bovine serum; (C) cells in Tpo (200 U/mL); (D) cells in IL-3 (3 ng/mL); (E) cells in IL-11 (50 ng/mL); and (F ) cells in Tpo plus IL-11. The results shown here are representative of two experiments.