Drug dose versus ZR-75-1 cell proliferation inhibition rate curve (A) and Drug dose versus BT-474 cell proliferation inhibition rate curve (B) using trastuzumab or fulvestrant treatment or both.

<p>After 72h of continuous exposure to drugs (either trastuzumab or fulvestrant as single agents) higher cell proliferation inhibition rates were observed with increasing drug concentrations (P<0.05). The combination of both drugs led to much stronger effect compared with individual drug treatments in both cell lines (P<0.05); ED₅₀ values have been indicated in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0168960#pone.0168960.t001" target="_blank">Table 1</a>.