The document describes immunohistochemistry protocols for analyzing α-smooth muscle actin (α-SMA) in paraffin-embedded tissue samples from human uterus cancer, human stomach, rat kidney, mouse liver, and mouse kidney. The protocol involves tissue processing, antigen retrieval using citric acid, inhibition of endogenous peroxidase, blocking with BSA, primary antibody incubation, secondary antibody incubation, DAB staining, hematoxylin counterstaining, dehydration, clearing, and visualization under a microscope. The α-SMA monoclonal antibody was diluted at 1:200 for overnight incubation at 4°C.