Recognition of native OPN by anti-OPN MAb. A) Human milk OPN was used in ELISA, and 1F11 and 2F10 binding compared to an irrelevant antibody (MAb 1E3, control). B) Whole kidney lysates were collected from wild type (WT) mice, OPN heterozygous mice (Het), and OPN null mutant mice (Null). Lysates were loaded equally and analyzed by SDS-PAGE followed by immunoblotting using 1F11. Recombinant OPN was used as a control. C) Human aortic smooth muscle cells (SMC) were transduced with activated Notch1 receptor  to increase OPN expression, and compared to human umbilical vein endothelial cells (EC). Both 2F10 and 1F11 recognize OPN in SMC.