The invention concerns the field of cell culture technology. The invention describes production host cell lines comprising vector constructs comprising a CERT S132 A expression cassette. Those cell lines have improved growth characteristics and high CERT S132A expression levels. The invention especially concerns two cell lines deposited with the DSMZ under the number DSM ACC2989 (CHO/CERT 2.20) and DSM AC-C2990 (CHO/CERT 2.41). The invention further concerns a method of generating such preferred production host cells and a method of producing proteins using the two cell lines deposited with the DSMZ under the number DSM ACC2989 (CHO/CERT 2.20) and DSM ACC2990 (CHO/CERT 2.41).
