All lanes : Anti-Cripto1 antibody ( ab31195 ) at 1 µg/ml Lane 1 : Cripto protein Lane 2 : Cripto protein with Human Cripto1 peptide (ab23309) at 1 µg/ml Lysates/proteins at 0.1 µg per lane. Secondary Rabbit IgG secondary antibody ( ab28446 ) at 1/10000 dilution Predicted band size : 21 kDa Observed band size : 17-21 kDa ( why is the actual band size different from the predicted? )