MCTS1 and neoplasm: It is importantthat elevation of MCTS1 expression increases the level ofCD44, a tumor stem cell marker [57].Treatment of the cells ectopically expressing MCTS1 with theIL-6 cytokine leads to an even more rapid formation of mammospheres; therefore,MCTS1 may be involved in the regulation of IL-6 signaling(Fig. 5).Treatment of cells with tocilizumab, a monoclonal antibody thatinhibits the IL-6 receptor, reduces the intensity of mammosphere formationunder MCTS1 induction and also significantly decreases thenumber of cells CD44+/CD24- subpopulation to a control level [57]