WWP2 and Nephropathy: The protective effect of WWP2 deficiency was confirmed in the folic acid–induced nephropathy model.62 Twenty-one days after folic acid induction, histochemistry for Sirius red and Masson's trichrome showed reduced fibrotic lesions, associated with a lower percentage of cortical fibrosis and collagen content in WWP2−/− when compared with WT controls (Figure 2, E and F).