MKI67 and neoplasm: In the control SKBr3 tumors, trastuzumab treatment, with or without NAC supplementation, resulted in a decrease in Ki67 positive tumor cells compared to the respective controls (CT = 15.3 ± 1.6 % vs CS = 26.7 ± 1.8 and NT = 14.9 ± 1.6 vs NS=25.8 ± 1.5; p < 0.001 and p = 0.028) (Figure 5B).