A short chain synthetic antigenic peptide (GILGFVFTL) derived from the influenza virus A matrix protein and presented by HLA-A2 major histocompatibility complex (MHC) class I molecules. Flu matrix peptide p58-66 stimulates the lytic functions of cytotoxic T lymphocytes (CTLs), which may result in the eradication of virus-infected or malignant tumor cells.