ELISA identifies only Pln.D1 but not Pln.D3-5 in enriched rhPln.198. The enriched high Mr rhPln.198 synthesized by HEK 293 cells was used to coat microtiter wells that were subsequently blocked then incubated with 1.7 μg/ml of different primary antibodies as depicted in the legend. ELISA was completed as described in Methods. Background signal for each antibody binding to uncoated wells was subtracted to produce the net signal. Inset: ELISA data showing negligible mAb A76 reactivity against rhPln.247 and strong reactivity with full-length endothelial perlecan (purified as previously described ), while mAb A71 reacted strongly to both the native perlecan and the truncated recombinant. Net absorbance minus buffer-coated wells represented.