IL4 and cystic fibrosis: Research is currently being performed to elucidate the mechanism(s) responsible for the increased levels of surface CXCR2, however, exposure to intermittent hypoxic conditions [45], IL-4/IL-13 [46], and OxLDL [47] in vitro has been demonstrated to result in increases in CXCR2 levels and may be relevant to the mechanism(s) involved in the increased CXCR2 observed during CF.