(A) Western blots for the detection of MKLP1, MgcRacGAP, and ECT2. HeLa cells were transfected with siRNA targeting luciferase, MKLP1, MgcRacGAP, or ECT2, respectively. Loading control: α-tubulin. (B) HeLa cells treated with luciferase, MKLP1, MgcRacGAP, or ECT2 siRNAs were fixed and immunostained with pLC1. Bar, 10 µm. (C) Quantitative analysis of 1P-MRLC fluorescence at the contractile ring in cells depleted of luciferase, MKLP1, MgcRacGAP, or ECT2. The averages of at least 2 independent experiments are shown. Error bars indicate the standard error of the mean (±SEM). *p<0.05, **p<0.01 (t-test). n ≥15. (D) HeLa cells treated with luciferase, MKLP1, MgcRacGAP, or ECT2 siRNAs were fixed and immunostained as indicated. (E) Quantitative analysis of 2P-MRLC fluorescence at the midzone in cells depleted of luciferase, MKLP1, MgcRacGAP, or ECT2. Error bars indicate ±SEM. (F) HeLa cells treated with 10 µM Y-27632 or 10 µM ML-7 for 30 min were fixed and immunostained with CS1P pAb or 4F12. Bar, 10 µm. (G) Quantitative analysis of 1P-MRLC fluorescence at the contractile ring in cells treated as indicated. Representative data from 2 independent experiments are shown. **p<0.01 (t-test). n ≥11. (H) Quantitative analysis of 2P-MRLC fluorescence at the midzone (white bar) or contractile ring (black bar) in cells treated as indicated. Representative data from 2 independent experiments are shown. **p<0.01 (t-test). n ≥17.