Highly transfectable derivative of the human primary embryonal kidney cell line 293 carrying a plasmid containing the temperature sensitive mutant of SV-40 large T-antigen (tsA1609neo).&Nbsp;&Nbsp;&Nbsp;Split confluent culture 1: 4 - 1: 5 every 2-3 days (without using trypsin/EDTA, cells can be detached by tapping the flask).