 Hello colleagues! You are stressed to select a highly productive clone? I mean you would like to express high amounts of recombinant protein in a mammalian cell line? We are the same problem. What you usually do? You will take a host cell line, for example C-H-O cell line, and you will transfer the cell line to the surgeon of interest. After this procedure, you will obtain a pool of clothes. So far so good, but now it's going to be complicated. Your pool consists of a mixture of clones, but unfortunately the majority of clones are medium or even low producers. And how you can find your desired but rare highly productive clones? In order to overcome this problem, a very time consuming amplification and selection procedure is performed normally. But we had another idea. Maybe it should be possible to select such a highly productive cell line with a much easier system. And now I will ask you again. You are stressed to select a highly productive clone? It's normal. People which are very busy are often stressed. But what's up with your clones? Are they also stressed by the overexpression of proteins? It has been suspected that even the overexpression of native proteins can provoke ER stress, which activates the unfolded protein response. We have proved this suggestion by using a very smart approach called Bacombinase-Mediate-Cosaptic-Change-RMCE. I will show you. This is the approach we have tested several ER stress response elements, like transcription-factor binding sites, for example, unfolded protein response, amino acid response, or ER stress response elements, and various ER stress-related cellular promoters. All of these elements were introduced into the same genomic integration site of an antibody-expressing C-H-O cell line by using RMCE. In this way, we found that overexpression of a recombinant antibody results in an increased activity of the GRP-78 promoter. Interestingly, a strong correlation between the amount of the secreted antibody and its activity was observed. Based on these results, we have concluded that the ER stress-based selection system developed during this study should be suitable to identify and isolate your desired highly productive clones. We have published all of our thoughts. My name is Lars Kober and my co-authors are Christoph Zehe and Jürgen Boeder. Our current article entitled Development of a Novel ER Stress-Based Selection System for the Isolation of Highly Productive Clones is published in the journal Biotechnology and Bioengineering. Thank you for listening and happy reading.