Figure 1. Abnormally expressed genes associated with IVDD identified using the GSE167199 and GSE15227 datasets. (A, B) Heatmap of all differentially expressed genes in degenerative intervertebral disc and nondegenerative intervertebral disc tissues from the GSE167199 and GSE15227 datasets. (C) Venn diagram showing the two selected transcription factors. (D) early growth response protein 1 (EGR1) was identified as a key gene. (E, F) EGR1 expression was analyzed by using the GSE167199 and GSE15227 datasets. (G) A volcano plot was created using RNA-seq data to show differentially expressed genes. (H) Bubble chart showing the KEGG pathway analysis of the RNA-seq data.