ABCC6 and Pseudoxanthoma elasticum: Though TGFβ has already been suggested to be involved in PXE by Jiang et al., who reported that ABCC6 promoter activity can be modulated by several cytokines including TGFβ [74], it was somewhat unexpected to find only overexpression of TGFβ-2 in PXE fibroblasts, while expression of the other ligands (TGFβ-1 and TGFβ-3) remained the same as in controls.