Below is an SDS-PAGE (A) of an induced lysate (Lane 2) and a…

Below is an SDS-PAGE (A) of an induced lysate (Lane 2) and a western blot (B) using an anti-target protein antibody. The protein was purified via affinity chromatography (Lanes 4-6). What is the molecular weight of the major contaminant (not the target protein) that was removed by the purification?