Mitomycin A is a bacterial metabolite originally isolated from S. caespitosus. It reduces migration inhibition factor (MIF) production by isolated human lymphocytes when used at a concentration of 0.25 µg/ml and decreases spontaneous migration of WEHI-3 murine monocytes when used at concentrations of 0.5 and 5 µg/ml. Mitomycin A forms intra- and interstrand adducts with DNA in the presence of thiols, such as dithiothreitol (DTT). It reduces tumor growth in P388 leukemia and B16 melanoma mouse models with a minimum effective dose (MED) of 0.05 mg/kg for both but is toxic to mice with an LD50 value of 2 mg/kg.