FZD4 and neoplasm: Thus, we determined whether we could recapitulate the effects of genetic inactivation on the development of a tumor-permissive stroma by short-term treatment of Ptch+/−mice with a function blocking Fzd4 antibody (αFzd4), which has been previously shown to effectively cross the BBB and impact retinal vasculature (Paes et al., 2011) (Figure 7—figure supplement 1).