Figure 4 DEGs were validated in LUAD and normal lung tissue. The gene expression of (A) PECAM1, (B) CDK1, (C) MKI67, (D) SPP1, (E) TOP2A, (F) CHEK1, (G) CCNB1, (H) RRM2 in 483 LUAD patients and 347 normal tissues was evaluated by GEPIA. The relative mRNA expression levels of (I) PECAM1, (J) CDK1, (K) MKI67, (L) SPP1, (M) TOP2A, (N) CHEK1, (O) CCNB1, and (P) RRM2 between 28 LUAD patients and 8 normal lung tissues were determined by RT-qPCR. All data are shown as the mean±SD, ### P<0.001 versus the normal group. DEGs – differentially expressed genes; LUAD – lung adenocarcinoma; GEPIA – Gene Expression Profiling Interactive Analysis; mRNA – messenger RNA; RT-qPCR – real-time quantitative polymerase chain reaction; SD – standard deviation.