ERBB4 and gastric cancer: To characterize the expression pattern of the four RTKs integrating the ErbB family (ErbB1/EGFR, ErbB2, ErbB3 and ErbB4), Western blot (WB) analysis was performed on whole cell lysates from four GC cell lines (NCI-N87, AGS, MKN45 and MKN74), representative for the heterogeneous nature of gastric cancer regarding ErbB2 status (Figure 1).