For example, Loxl1 knockout mice (Loxl1−/− on a mixed C57BL/6J and 129S1/SvImJ background) have abnormal elastic fiber appearance in the uterine tract postpartum, resulting in pelvic organ prolapse, enlarged alveoli in lungs, increased skin laxity and vascular abnormalities with tropoelastin accumulation (Liu et al., 2004). This evidence concerns the gene ELN and pelvic organ prolapse.