Our results showed that: (1) PMP22 is significantly upregulated in human gastric cancer cell lines and clinical samples (Fig. 1); (2) Downregulation of PMP22 suppressed gastric cancer cell proliferation (Fig. 2); (3) PMP22 inhibits etoposide-induced cell apoptosis in gastric cancer cells (Fig. 3); (4) PMP22 suppressed p53 transcriptional activity upon etoposide treatment; (Fig. 4-5); (5) PMP22 enhanced tumorigenicity in vivo in nude mice and inhibited etoposide-induced tumor growth inhibition (Fig. 6-7). This evidence concerns the gene TP53 and neoplasm.