Figure 5. Cancer stem-like cells have active Wnt signaling in the retinoblastoma cell lines. The percent of co-localized Msi1 and nuclear β-catenin was quantified in the Weri and Y79 cell lines. Immunohistochemistry demonstrated that tumor stem cells (Msi1+) were more often positive for nuclear β-catenin than non-stem cells (Msi-), indicating active Wnt signaling. The difference in nuclear β-catenin was statistically significant at p<0.001 (*). The experiment was repeated five times.