EGFR and squamous cell carcinoma: To investigate whether fusion proteins efficiently bind to EGFR, A431 cells that were derived from a human epidermoid carcinoma characterised by high levels of EGFR expression, were incubated with different concentrations of 6His-tagged TGFαL3SEAD227A or SEAD227ATGFαL3, or rSEA (from 0.1 ng/μl to 1 ug/μl).