 The number of novel recombinant protein therapeutics approved by the FDA from 2006 to 2011 increased significantly, leading to a surge in demand for production cell lines with high productivity. Mammalian cell line development technologies currently used by most biopharmaceutical companies are based on either the Methatrexate, MTX amplification technology or the glutamine synthetase, GS system. These technologies produce highly heterogeneous cell clones due to random integration of the gene of interest and amplification of the gene. This results in a long and laborious process of screening many cell clones to find rare stable high producers. To address this issue, advancements in protein expression and clone screening technologies are needed to increase the speed and efficiency of generating robust and highly productive cell lines. This article was authored by Seikong Ying, Tingfeng Lai and Yuan Qingyang.