FIGURE 4.

Marked increase in the EV-mediated EGFR emission from EKI-treated cancer cells. A, unchanged levels of EGFR protein in lysates of A431 cells cultured for 24 h in the presence of control medium (control), CI-1033 (5 μm), PF-00299804 (5 μm), or Cetuximab (Cetux., 50 μg/ml), as measured by ELISA. B, unchanged levels of EGFR protein in lysates of A431 cells cultured in the presence of CI-1033 (5 μm), TGFα (50 ng/ml), or both (EGFR ELISA). C, dramatic increase in EGFR signal in the EV (P4) fraction of the conditioned medium corresponding to CI-1033 and PF-00299804 treatment; pooled data were from two independent experiments. D, increase in EV-mediated emission of EGFR upon treatment with CI-1033 and TGFα/CI-1033. The combined treatment highlights the ability of EGFR kinase inhibitor to trigger EV release; p values were as indicated. The results were independently reproduced using an antibody array (data not shown). NS, not significant.