<prompt> Answer this question truthfullyWhat is M protein, and where is it typically found in bacterial cells?  <response>: <reason> M protein is a virulence factor that is produced by Streptococcus pyogenes GAS bacteria. It is an anti-phagocytic protein that helps the bacteria evade the immune system by preventing phagocytosis ingestion by immune cells. M protein is typically found on the surface of GAS cell walls, where it plays a key role in the pathogenesis of streptococcal infections. 