EGFR and squamous cell carcinoma: As shown in Fig S7, EGFR phosphorylation was detected in neither A431 cells (a human epidermoid carcinoma cell line; PTPRHhigh), HepG2 cells (a human hepatocellular carcinoma cell line; PTPRHlow), nor MIA-PaCa-2 cells (a human pancreatic carcinoma cell line; PTPRHlow) in the steady-state condition.