Analysis of the EGFR-binding properties. Cell-binding and internalization studies of 133La-labeled macropa-sdAb conjugates were performed using the human epidermoid carcinoma cell line A431 and the squamous carcinoma cell line FaDu characterized by high and moderate EGFR expression, respectively (see supplemental Fig. 18 for comparative, ELISA-based quantification of full-length EGFR in respective cell lysates). Here, EGFR is linked to squamous cell carcinoma.