Linearity tests on human samples. (A) Representative data for linearity test of BACE1 ELISA on platelet lysates. Two-fold serial dilutions of platelet lysate (5, 10, 20, and 40 μg total proteins) were prepared in PBS and heat-denatured at 50 °C before loading. We observed a good linearity of the signal with the corrected OD values doubling as the quantity of total protein increased (y = 0.0076x − 0.0006; R2 = 0.967). (B) Human plasma was diluted to 0.8–75% in PBS and heat-denatured before loading. We noticed good linearity for dilution up to 15% (inset; y = 7.9188x − 0.1252; R2 = 0.998). Above 15%, there had saturation of the signal, likely due to matrix effects.