Prognostic value of DDX39 in ER-positive BC. A) DDX39 impacts poor overall survival (OS) of ER-positive BC in the GEO pooled dataset. B) DDX39 predicts poor OS of ER-positive BC in TCGA pooled dataset. C) Stratification analysis for DDX39 and OS/ PFS was conducted on pooled GEO dataset in ER-positive BC patients. The OS results were displayed on the left and PFS on the right. Participants were stratified by age, tumor size, lymph node, PR, MKI67, Elson grade and region. Asia subgroup includes GSE3494 and GSE20685 dataset; Europe subgroup contains GSE1456, GSE4922, GSE53031, GSE22220, GSE21653, GSE42568 and NKI dataset; and North America subgroup comprises GSE22226, GSE7390, GSE2034, GSE10885, GSE25066, GSE6532, GSE20624 and GSE7849 datasets. Cox analysis was conducted on each stratified subgroup.