Th€ Molecular Analysis on the Expression of Oral Mucosa Protein Anomaly in R€curr€nt Aphthous Stomatitis (RAS) The purpose ofthis study was to disclose one of the etiopathogenesis ofrecunent aphthous stomatitis (RAS) at nol€cular level by analyzing the exFession of protein anomaly in oral mucosa. This was a crosssectional explorative and analfic observational study. Samples, who met inclusion and exclusion criteria, wer€ taken fiom total population. Samples of protein swab w€re obtained from oml mucosa, serum were taken from 15 patients with major RAS, 20 patients with minor RAS and 15 wer€ control. The characterization of protein anomaly expressed on the surface of oral mucosa epithelium was carried out using SDS-PACE 12% and Westembiot methods. The result of oral mucosa protein anomaly expressjon analysis in patients with major RAS using SDS-PAGE 12% revealed five prot€in bands with molecular weights of 87, 65, 30,25, and 20 kDa. In minor RAS cases with protein anomaly expression there were four prot€ins wirh mol€cular weights of8?, 65,25, and 20 kDa" and th€ protein in remission RAS had four proteins bands with molecular weight of87, 65, 25 and 20 kDa. The band disappeamnces by using Westemblot test, of30 kDa of major cases, 87 and 20 kDa ofminor cases and 20 and 25 kDaofr€mission cases, indicaled that those patients were not reacted with polyclonal antibodjes of rabbit serumi th€refore they had no role in the induction of RAS-ln conclusion, the antigenic protein exFessed in oral mucosa ofmajor, ninor, and remission RAS was predominantly 65 kDa molec\ulat weighr.