To elucidate the molecular mechanism of renal fibrosis mediated by PTC-specific p300, we first treated primary renal proximal tubular epithelial cells (PTECs) with transforming growth factor-β (TGFβ), a well-known fibrotic stimulus, and observed a time-dependent increase in p300 protein levels (Appendix Fig. S8A). The gene discussed is TGFB1; the disease is renal fibrosis.