Changing Proteins in Granulosa Cells during Follicular Development in Pig In-Soon Chae1, Dong-Min Jang3, Hee-Tae Cheong2, Boo-Keun Yang1 and Choon-Keun Park1,† 1College of Animal Life Sciences, 2School of Veterinary Medicine, Kangwon National University, Chuncheon 200-701, Korea 3CHA Stem Cell Institute, CHA Hospital, Seoul 463-712, Korea ABSTRACT This study analyzed change of proteins in granulosa cells during the porcine follicuar development by proteomics techniques. Granulosa cells of the follicles, of which the diameter is 2～4 mm and 6～10 mm, were collected from ovary of slaughtered pig that each follicle of diameter 1～4 mm and 6～10 mm. We extracted glanulosa cell proteins by M-PER Mammalian Protein Extraction Reagent. Proteins were refined by clean-up kit and quantified by Bradford method until total protein was 200 μl. Immobilized pH gradient(IPG) strip used 18 cm, 3～10 NL. SDS-PAGE used 10% acrylamide gel. After silver staining, Melanie 7 and naked eye test were used for spot analyzation. Increasing proteins in glanulosa cell of 6～10 mm follicle were 7 spots. This spots were analyzed by MALDI-TOF MS and searched on NCBInr. In results, 7 spots were similar to zinc/ling finger protein 3 precursor (RING finger protein 203), angiomotin, heat shock 60 kDa protein 1 (chaperonin) isoform 1 (HSP60), similar to transducin-like enhancer protein 1 (TLE 1), SH3 and PX domains 2A (SH3PXD2A). Those proteins were related with transfer between cells. Increase of proteins has an effect on follicular development.