Effect of the combination of 8Q or NCS with PTX in MDA-MB-231 mammospheres. (A) Mammosphere-forming (MSF) efficiency of PTX, 8Q, NCS and their combination (2 μM, 25 μM and 4 μM, respectively). (B) Mammosphere viability (MSV) of PTX, 8Q, NCS and their combination (4 μM, 50 μM and 8 μM, respectively). Results are represented as the mean ± SEM of three independent experiments and referred to as the non-treated control condition. Statistical t-test analysis was performed comparing combination therapy with single anti-CSC treatments at the corresponding equivalent drug dose (* p < 0.05, ** p < 0.01, *** p < 0.001).