2.1. Cell Culture and Transfection

The 93-VU-147T cell line was obtained from VU University Medical Center Amsterdam (Department for Clinical Genetics, Amsterdam, the Netherlands), UPCI-SCC-111 and -154 cell lines were obtained from DMSZ (Braunschweig, Germany), and UD-SCC-2, -5, and -7 cell lines were obtained from the University of Düsseldorf (Düsseldorf, Germany). All squamous cell carcinoma cell lines were cultured in appropriate medium (DMEM, MEM, or RPMI, Invitrogen, Darmstadt, Germany), supplemented with 10% fetal bovine serum (FBS, Gibco) and 100 μg/mL penicillin and 100 μg/mL streptomycin (Sigma Aldrich, St. Louis, MO, USA), and stored in an incubator (37 °C, 5% CO₂).