Chemotherapeutic effects on normal human mammary epithelial cells in passage 16 (HMEC P16). HBCEC derived from a 40 year-old (HBCEC 366) (Fig. 3A) and a 63 year-old (HBCEC 367) (Fig. 3B) woman both with ductal breast carcinoma, the breast cancer cell lines MCF-7 (Fig. 4A) and MDA-MB-231 (Fig. 4B), and normal HMEC in passage 16 (Fig. 5) were incubated with a single dose of 1 μM (blue bars) and 125 nM (red bars) of appropriated chemotherapeutic compounds (Taxol, Epothilone A, Epothilone B, Epirubicin, Doxorubicin) and certain anthracyclin combinations (Epirubicin/Taxol, Epirubicin/Epothilone A, Epirubicin/Epothilone B) for 6d, respectively. Alternatively, the drugs were replaced after 3d, resulting in a similar 6d (= 2× 3d) incubation of the same compounds, using concentrations of 1 μM (yellow bars) and 125 nM (turquoise bars), respectively. Whereas the higher concentration of 1 μM was generally more effective, this was further promoted by a sequential treatment. Moreover, the HBCEC populations revealed distinct effects to the anticancer drugs Epothilone A and B, suggesting an individual responsiveness specific for the appropriate patient (Fig. 3A, B). Similarly, Epothilone A and B exhibited different effects on the two breast carcinoma cell lines. Furthermore, the non-metastatic MCF-7 cell line displayed an overall increased sensitivity to the administered drugs or drug combinations as compared to the highly metastatic MDA-MB-231 cells (Fig. 4A, B). HMEC (P16) demonstrated reduced cytotoxic effects of the chemotherapeutics as compared to the HBCEC cultures (Fig. 5). Data represent the mean +s.d. (n = up to 5 replicates). P values were calculated by the unpaired T-test according to the appropriate untreated control cells (Control). Results were considered as statistically significant when P value was < 0.5 (*P < 0.5; **P < 0.05; ***P < 0.005).