ERBB2 and breast cancer: The antiproliferative activity showed compound 18 was potent with an IC50 value in lower micromolar (0.868±0.032 μM), whereas, as reported in our previous publication, for Calu-3 cell lines that overexpress HER2 IC50 was 0.018 ± 0.013 μM and in HER2 positive breast cancer cell lines BT-474 and SKBR-3, IC50 was 0.197 ± 0.055 and 0.194 ± 0.046 μM respectively.