Proliferation and cell cycle progression of G1E-ER2 cells by stromal cells expressing different isoforms of SCF.

G1E-ER2 cells were cocultured for 48 hours with mitomycin C–treated parental Sl/Sl4 stromal cells or stable stromal cell transfectants expressing S-SCF, MA-SCF, or MR-SCF. (A) Proliferation was measured by thymidine incorporation assay. Bars denote the mean thymidine incorporation (counts per minute [cpm] [± SEM]) of 2 independent experiments performed in replicates of 6. *P < .05 S-SCF, MA-SCF, and MR-SCF versus Sl/Sl.4 **P < .001 S-SCF versus MR-SCF and MA-SCF. MR-SCF versus MA-SCF, P = .2. (B) Cell cycle analysis was performed by propidium iodide staining of G1E-ER2 cells. Percentages of cells in different phases of cell cycle are indicated. Shown is a representative experiment. Similar results were observed in 2 independent experiments performed in replicates of 3.