ABCC6 and pseudoxanthoma elasticum (inherited or acquired): As our group recently demonstrated that increased DDR activation is involved in the pathogenesis of ectopic calcification in PXE patient-derived dermal fibroblasts and lesional skin tissue as well as in a vertebrate PXE animal model (Danio rerio) [12], we evaluated whether a similar mechanism is also present in Abcc6−/− mice.