RPS6KA1 and renal fibrosis: Thus, in tPA-mediated profibrotic pathway, p90RSK activation not only promotes fibroblast survival through p90RSK/Bad/cytochrome C pathway; but also induces fibroblast proliferation through p90RSK/GSK-3β/cyclin D1 signaling (Lin et al., 2010; Hu et al., 2008), which together lead to fibroblast accumulation in the diseased kidneys resulting in progressive renal fibrosis (Figure 4).