AQP1 and renal fibrosis: Next, to examine the cell type-specific expression of p300 in kidney tissues from renal fibrosis mouse models, we performed serial immunohistochemistry (IHC) staining using antibodies against proximal tubules (aquaporin-1, AQP1), collecting ducts (aquaporin-2, AQP2), glomeruli (Wilms tumor protein, WT1), and blood vessels (PECAM1, CD31), and evaluated changes in p300 expression in each cell type by H-scoring.