This protein marker is designed for convenient protein band identification in fluorescent Western Blotting. It is a lyophilized mixture of five recombinant proteins that are able to bind to primary and/or secondary antibodies derived from a wide range of host species. It thus enables direct visualization of both the protein marker and users' samples on the same western blot membrane without any additional reagents. Calculation The apparent molecular weights of its five protein bands are 22 kDa, 40 kDa, 60 kDa, 85 kDa and 120 kDa. Note 1. Non-BSA based blocking reagents (such as 5% skimmed milk) are recommended for blocking.2. For best results, the loading volume of the marker should be optimized for different experiment conditions (from 2.5 μl to 10 μl).3. This marker binds to the constant region of IgG, so protein A or protein G fluorephore conjugates cannot be used as the secondary antibody.