Nonidet® P40 (substitute) is a non-ionic, non-denaturing detergent suitable for solubilizing and isolation of membrane proteins. Has been used to solubilize cerebral GABA receptors. Also useful in solubilization of proteins and lipids of the scallop gill ciliary membrane and of membranes from breast cancer tumors. Chemically indistinguishable from Nonidet P-40, which is no longer commercially available.