Abstract: Objective: To investigate the suncellular localization of autophosphorylated Pak1 in mouse oocytes during meiosis and its correlation with spindle formation. Methods: Western blot procedure was employed to assay the dynamic changes in protein expression of autophosphated Pak1 at Ser144(pPak1S144); immunofluorescence staining was carried out to label pPak1S144 subcellular distribution and its temporal-spatial relationship with spindle and microtubule organizing centers(MTOCs) proteins, Pericentrin and ?-tubulin. Results: pPak1S144 is co-localized with Pericentrin and ?-tubulin and concentrated on spindle poles. Conclusion: pPak1S144 is MTOC-associated protein, implying a role in meiotic spindle formation.

Key words: pPak1S144, oocytes, meiosis, MTOC, spindle