ACTA1 and systemic sclerosis: However, it is important to consider that even profibrotic α-SMA+ fibroblasts have been demonstrated to express PDPN in a variety of disorders, including SSc-related cutaneous fibrosis and cardiac fibrosis [25,27], and that PDPN can be considered not only a reliable myofibroblast marker [24], but also a marker of aggressiveness in tumors, as this transmembrane glycoprotein promotes cancer cell migration and invasion, and is highly expressed in cancer-associated fibroblasts [26,28,29].