DLL4 and polyposis: RNA was analyzed by quantitative reverse transcriptase‐polymerase chain reaction for the expression level of (1) Notch pathway components such as receptors (NOTCH1‐4), ligands (DLL4, JAGGED‐1), and target genes (HEY1, 2, and HES1) and (2) genes providing information on the pathogenesis of polyposis (C‐MYC and SCGB1A1) and on eosinophils content (CCL26, IL5, and SAA2).