Total RNA (0.7 μg) and the oligo-dT primers
were used for the first strand DNA synthesis using M-MuLV First Strand
cDNA Synthesis Kit (Sangon Biotech, China) according to the manufacturer's
instructions. By using the cDNA as a template, PCR analysis was
performed with primers EGFP-F/EGFP-R and programs mentioned
above. The primers, 18S-F (5′-ACTTCTTAGAGGGACTATTGGCG-3′) and
18S-R (5′-CCTTGTTACGACTTCTCCTTCCT-3′) were used to amplify the
18S rRNA gene fragment (391 bp) as an internal standard.