MATERIALS AND METHODS: The MB interaction with NADH, FADH RESULTS: NADH has been established to be the main coenzyme with which MB interacts. The reduction of the lactate quantity is mediated by the shift of tumor metabolism as a result of MB interaction with the NADH. In the experiments CONCLUSION: The possibility of using MB for the tumor metabolism correction and growth rate reduction has been demonstrated, however, the time of therapy and MB concentration should be optimized to obtain more pronounced therapeutic effect.