Solid-phase printed arrays of square-shaped 'blots' of immobilized BMP2 will be printed on sialanized fibrin-coated glass cover slips. The blots will be 750 um x 750 um and spaced 1.75 mm apart in a 4 x 4 array. There will be blots with 4 different concentrations of BMP2, ranging from zero to binding site saturation, along each column, and there will be 4 replicates of each column.