CLN5 and Pseudoxanthoma elasticum: However, limited information is available on the key cellular pathways of soft tissue mineralization, the TGFβ superfamily-related signalling - its ligands (TGFβ1-3, BMPs), its receptors (TGFβR1/2, BMPRI/II) and its intracellular signal transducers (SMADs - Mothers Against Decapentaplegic homolog proteins) -, Wnt signalling, apoptosis or ER stress, in PXE.