CHO 4Tx® is a unique CHO transfection system developed by ExcellGene, a Swiss industry leader in complex recombinant protein expression in CHO cells, and the fruit of over two decades of experience as a contract development and manufacturing organization specialized in challenging protein expression services. CHO 4Tx® is dedicated to the discovery and preclinical research steps for new diagnostics or drug development processes, when large numbers of protein variants are needed in small amounts (from mg to g scale) to perform fast and efficient screening programs.