The IRIS9 Plus Prestained Protein Ladder is a combination of 9 pre-stained proteins with molecular weights from 15to 170 kDa. The 9 recombinant proteins are covalently coupled with blue chromophore, while 1 green band at 15kDa, a red band at 70 kDa and a newly designed peacock green band at 60 kDa serve as reference bands. The IRIS9Plus Prestained Protein Ladder keeps track of the size and separation of proteins during SDS-polyacrylamide gelelectrophoresis, approximating the target protein size and validating the Western transfer efficiency on PVDF, nylon,or nitrocellulose membranes.