αFzd4 treatment of Ptch+/−mice at P7 and P16 was sufficient to phenocopy the enhanced tumor initiation phenotype of our compound mutant models, increasing MB incidence from 69% in animals injected with anti-keyhole limpet hemocyanin (αKLH) control antibody to 93% in those injected with αFzd4, and significantly reducing mean tumor latency from 167 to 104 days (Figure 7A). Here, PTCH1 is linked to neoplasm.