CFTR and neoplasm: In a functional test of Cftr deficiency, Than et al. reported that in mice carrying an intestinal specific Cftr conditional knockout allele crossed to the tumor-sensitized ApcMin mouse, mice deficient for Cftr (both heterozygotes and homozygotes) developed significantly more tumors than ApcMin mice that were wildtype for Cftr. Furthermore, invasive lesions were only observed in the Cftr-deficient cohort.