Model for sfSGK-dependent meiotic resumption in ovarian oocytes. A model for 1-MA–induced meiotic resumption in ovarian oocytes was prepared on the basis of previous and current findings. 1-MA stimulus induces Gβγ-dependent PI3K activation. In a manner that depends on PI3K, PDK1 and TORC2 activate sfSGK. Activation of sfSGK is essential for cyclin B–Cdk1 activation and sfNHE3-dependent pH_i increase. These SGK-dependent pathways prefer lower pH_i (magenta box). Processes leading to GVBD after cyclin B–Cdk1 activation prefer higher pH_i (green box). After GVBD, actin-dependent chromosome gathering and microtubule organization for spindle assembly as well as cytoplasmic granule invasion into the GV region require a pH_i of ∼7.0 or higher (cyan box) although spindles contains unaligned chromosomes at pH_i ∼7.0. Because the pH_i of ovarian oocytes before 1-MA stimulation in the body cavity is ∼6.7, the sfSGK-dependent pH_i increase accelerates GVBD and is required for the processes leading to meiotic spindle assembly in ovarian oocytes. By contrast, the pH_i of isolated oocytes before 1-MA stimulation in ASW is ∼7.0, which is already permissive for the processes toward spindle assembly.