Transfection

C2C12 myoblasts and NCI-H1299 cells were stably transfected with the following plasmids: pcDNA3.1-p53 (Wt-p53), four mutants (single mutants: p53C124S, p53C277S, p53C275S and triple mutant C124-277-275S) or pcDNA3.1 empty vector (kindly donated by Dr. Yvonne Sun, The Cancer Institute of New Jersey, NJ and Dr. Marikki Laiho, Marikki Laiho, Haartman Institute, Department of Virology, University of Helsinki, Hensinky) by electroporation using Nucleofector 4D® (Lonza, Sales) according to the manufacturer's instructions, and were immediately seeded into fresh medium. Transfection efficiency was estimated by co-transfecting the cells with pMAX-FP-GreenC vector (Lonza Sales). Only experiments that gave transfection efficiency of 80% were considered. Twenty-four hours after transfection (day 0), differentiation was induced.