RETNLB and cystic fibrosis: Most of these genes highly modified by the cocoa diet were not or were only slightly modified in the CF and I groups with the exception of Ros1 (an orphan receptor tyrosine kinase that plays a role in cell differentiation) and Tac4, which were also modified in the CF-fed animals, and Atf3 (activating transcription factor 3) and Retnlb (a cysteine-rich cytokine expressed in the colon and implicated in immunity) in the I-fed animals.