Evidence that the M protein interacts with the F and G proteins. Cells expressing the M protein (M), G and M proteins (GM), F and M proteins (FM) or F, G and M proteins (FGM) were immunoprecipitated (IP) with anti-M and immunoblotted (IB) with (A) anti-cmyc, (B) anti-FLAG or (C) anti-M. Cells expressing the F and M proteins (FM) or F, G and M proteins (FGM) were IP with (D) anti-cmyc or (E) anti-FLAG and IB with anti-M. The various G, F and M protein species are indicated. Cells transfected with pCAGGS are indicated (pc).