“…Total RNA from the groups of control, SHA0.2, CHA20, and CHA20/C at various passages of P1, P3, P5, and P7 was extracted with TRI Ò reagent (Sigma), and the cDNA was synthesized with reverse transcriptase (RT) system (Promega, Madison, USA) according to the manufacturer's protocol. Primer pairs of p16 INK4a : 5 0 -GCAGCATGG AGTCCGCTG CAGACA-3 0 (sense) and 5 0 -CGGATTTAGCTCTGCT CTTGGGAT-3 0 (antisense) [16], and glyceraldehyde-3-phosphate dehydrogenase (G3PDH): 5 0 -ACCACAGTCCATG CCATCAC-3 0 (sense) and 5 0 -TCCACCACCCTGTTGCT GTA-3 0 (antisense) [17] were synthesized. The amount of each template was adjusted to give PCR signal at the exponential phase.…”