Thermo Scientific PageRuler Prestained Protein Ladder is a mixture of 10 blue-, orange-, and green-stained proteins (10 to 180 kDa) for use as size standards in protein electrophoresis (SDS-PAGE) and western blotting. The protein ladder is supplied in a ready-to-use format for direct loading onto gels; no need to heat, reduce, or add sample buffer prior to use.