REN and pemphigus foliaceus: Other EC-relevant pathways that have been investigated in PF include (a) autotaxin, the enzyme responsible for generation of the profibrotic lipid mediator LPA, which also has phosphodiesterase activity and is highly expressed by ECs; (b) the integrins, including αvβ1 and αvβ6, which are implicated in PF and have important effects on EC function (132); (d) CTGF, which is potently fibrogenic and contributes to the development of IPF-PH; and, finally, (e) the renin-angiotensin system — in particular the ATR2 receptor — agonism of which attenuates vascular remodeling in models of PH (133).