Increased immunostaining of pSmad1, pSmad4, PSmad5, pSmad8 and pSmad1-5-8 and RUNX2 in PXE and Abcc6−/−murine tissues confirms that in PXE a coordinated activation of the BMP2- SMADs-RUNX2 signalling pathway occurs. This evidence concerns the gene ABCC6 and pseudoxanthoma elasticum (inherited or acquired).