A U.S. Patent Application for ” Cation Exchange Chromatography Methods”  was published by Bristol- Myers Squibb  on April 25th, 2019. The present invention provides improved methods of protein purification using CEX chromatography. Such methods generally comprise the steps of: contacting a protein of interest (e.g., an antibody) with a cation exchange resin at a first pH, that is less than the pI of the most acidic isoform of the protein of interest, such that the protein of interest binds to the resin; washing the cation exchange resin at a second pH that is greater than the first pH, but less than the p1 of the most acidic isoform of the protein of interest… Learn More