Strategy of primers. To avoid p53 pseudogene co-amplification, the upstream PCR primers P1, P2, and P3 in the region corresponding to introns 4, 5, and 7 were used in combination with downstream primers P4, P5, and P6 within the region corre-sponding to introns 5, 7, and 8 of p53 gene. Primers Pmu and Pmd for RT-PCR located in exons 7 and 8, respectively.