S100A9 and cystic fibrosis: Furthermore, no significant difference in either S100A8 or S100A9 expression levels was detected in non-airway tissue, including the ileum (tissue most severely affected in CF mice) or liver of CF compared to wild-type animals of both C57BL/6J and BALB/cJ strains (p ≤ 0.5, five mice for each group), as shown in Fig. 1C, indicating that increased levels of S100A8 and S100A9 expression were lung specific.