NOS3 and cystic fibrosis: On the other hand, in eNOS+/− mice, HFD did not induce a further enhancement of β‐cell mass (even reduced by 12% as compared to the CF group), but caused a significant increase in the number of extra‐islet β‐cell clusters, which are considered to be expression of β‐cell neogenesis and perhaps the first core of β‐cell aggregation to form new islets (Jetton et al., 2005).