FOXO1 and pulmonary fibrosis: Both Skp2-deficiency and treatment with the Skp2 inhibitor SZL-P1-41 increased p27 levels in the BLM-infused model suggesting that Skp2 targets p27 for degradation in pulmonary fibrosis; however, it has been reported that Skp2 targets many important proteins in addition to p27, including p21, p57, p130, p300, Tob1, FOXO1, Akt, and RASSF for ubiquitin-mediated proteasomal degradation [8,9,10,11].