RPS6KA1 and renal fibrosis: Thus, in tPA profibrotic signal pathway, p90RSK activation induces fibroblast accumulation and contributes to renal fibrosis through dual mechanisms: (1) to promote fibroblast survival through p90RSK/Bad/cytochrome C pathway; (2) to induce fibroblast proliferation through p90RSK/GSK-3β/cyclin D1 signalling [24,30].