PCSK9 and neoplasm: To explore the expression of PCSK9 in GC, we first evaluated the mRNA and protein expression levels of PCSK9 in paired GC and adjacent non-tumor tissues by qRT-PCR (n = 60; Figure 1A) and western blotting (n = 40; Figures 1B, C), the results showing that PCSK9 expression was significantly higher at both the transcriptional and protein level in the tumor tissues than in the adjacent normal tissues (P < 0.0001).