Figure 4. K5 induced K5R expression in Müller cells. Müller cells were exposed to 1% oxygen in the presence of 200 nM K5 at 37 °C for 12 h. Total RNA was isolated from the treated cells. The K5R mRNA was quantified with real-time RT–PCR and normalized by 18s RNA levels (mean±SD, n=3). The copies of K5R mRNA in hypoxia group were significantly lower than that in normoxia group (*p<0.05). K5 prevented the hypoxia-induced downregulation of K5R mRNA expression in cultured Müller cells.