Mouse monoclonal clone RET-P1 anti-Opsin antibody is used to tag opsin/rhodopsin for detection and quantitation by immunocytochemical and immunohistochemical (IHC) techniques such as immunoblotting, immunocytochemistry of cultured cells, immunohistochemistry (paraformaldehyde/glutaraldehyde-fixed, paraformaldehyde perfusion-fixed, frozen sections), immunoelectron microscopy, ELISA, competitive ELISA, and solid phase RIA. It is used as a probe to determine the presence and roles of opsin/rhodopsin in studies of rhodopsin location, functional properties and molecular mechanisms governing rod photoreceptor differentiation.