Ring myosin II activation is resistant to MLCK and PAK inhibitors. (A) Ring myosin II activation (P-MRLC) was monitored in MII oocytes after the following treatments (top to bottom): DMSO, ML-7 (15 µM, 1 h), Ca²⁺-free medium containing 1 mM EGTA and 10 µM thapsigargin (0Ca + Tg; 1 h), peptide-18 microinjection followed by a 3-h culture, Wortmannin (1 µM, 1 h), and IPA-3 (1 µM, 1 h). F-actin was labeled with Alexa Fluor 568–phalloidin. Chromosomes were stained with TO-PRO-3 (magenta). The scale bar is 10 µm and applies to the whole panel. (B) Bar graph illustrating the percentage of oocytes showing ring myosin II activation for each experimental condition. The number of oocytes scored is indicated above each bar. NS: not significant (Fisher’s exact test). (C) Box plot showing the intensity of ring P-MRLC staining for the same populations of oocytes as shown in B. NS: not significant (two-tailed Student’s t test).