CFTR and neoplasm: CFTR protein–protein interactions may also mediate tumor suppression by acting as a signaling hub with metastasis suppressor proteins of the NM23 (non-metastatic clone 23)/NDPK (nucleotide diphosphate kinase) family that have been proposed to negatively regulate the Ras/PI3K(phosphoinositide 3 kinase) signaling pathway (219).