Competition of ED-B FN staining by soluble recombinant ED-B FN. ED-B FN immunostaining was performed on paraffin-embedded serial sections of a clear cell renal cell carcinoma, using L19IL2, with (right) or without (left, positive control) preincubation of L19IL2 with an excess of soluble recombinant ED-B (magnification: ×150).