Ngb protein levels under four conditions: WT (wild type normal condition), WTOGD (wild type after O4/R4), Ngb-Tg (Ngb-transgenic normal condition), NgbOGD (Ngb-transgenic after O4/R4). A, Representative western blot showed Ngb level was slightly increased by O4/R4, and more significantly increased in Ngb-Tg under normal condition or after O4/R4. Actin served as equal loading controls. B, Relative Ngb protein levels were quantified by optical density of Ngb protein bands. Mean+SD, n=2 per group, *P<0.05.