Inhibition of the activity of signal molecules in mitogenic signaling cascade. The compounds inhibited EGF-induced phosphorylation of EGFR and its downstream signal molecules in mitogenic signaling. HeLa cells were treated with each compound (50 μg/mL for 40 min) followed by exposure to EGF (10 ng/mL for 10 min) except for the negative control (untreated). Proteins from the cells were resolved by 12% SDS-PAGE and immunoblotted with indicated antibodies. GAPDH was used as an internal loading control.