Cell lines [Tal3, TC-1 (positive control) and HEK293 (negative control)] were cultured in vitro and lysed in TRIzol. Cellular RNA was isolated using Direst-zol MicroPrep Kit (Zymogen) and cDNA was made using iScript Reverse Transcription Supermix for qRT-PCR (Bio-Rad) according to the supplied protocols. Gene transcript was amplified using the isolated RNA as a template and HPV16 E6 primers (forward, ACAAACCGTTGTGTGATTTGTT; reverse, CAGTGGCTTTTGACAGTTAATACA) with a Touchdown qPCR assay, as described previously (31 (link)). Subsequently, 1 μL of qPCR product was transferred to a 1% agarose gel with 0.01% ethidium bromide and run at 130V for 45 minutes. Resultant bands were visualized using the ChemiDoc Touch Imaging System (Bio-Rad).