TGFB1 and polyarteritis nodosa: Xiao et al. [23] observed significant podocyte apoptosis, a decreased p-Akt/Akt ratio, and increased activity of the TGF pathway in the PAN nephropathy rat model, suggesting that PAN induces podocyte apoptosis by activating TGF-β/Smad while blocking the PI3K/Akt pathway.