KDR and cancer: Compounds <b>7j</b>, <b>7k</b>, and <b>7o</b> (GI<sub>50</sub> values of 27, 25, and 30, respectively) demonstrated greater potency than erlotinib (GI<sub>50</sub> value of 33 nM), particularly against breast (MCF-7) cancer cell lines, and were identified as the most potent dual EGFR/VEGFR-2 inhibitors.