SEMA6A and metastatic neoplasm: Therefore, we next considered VEGF/Sema gene expression in datasets with metastatic tumors (Additional file 1: Table S1, note that only GSE6919, GSE21034, GSE32269, and GSE35988 contain both primary and metastatic tumors, while only GSE6919, GSE21034, GSE38241, and GSE35988 contain both normal prostate tissue and metastatic tumors).