Cell cycle after transfection with Notch1 overexpression plasmids in MM cells. Cell cycle analysis after transfection with Notch1 overexpression plasmids in RPMI-8226 cells (a, b). Cell cycle analysis after transfection with Notch1 overexpression plasmids in U266 cells (c, d). Comparison between two groups was determined by t-test. P value < 0.05 was considered significant. *, P < 0.05; **, P < 0.01; NS, no significance.