GDF6 and invasive breast carcinoma: GDF6 was significantly downregulated in 23 types of tumors, including glioblastoma multiforme (GBM) and breast invasive carcinoma (BRCA), while it was abnormally upregulated in seven types of tumors, such as kidney renal clear cell carcinoma (KIRC) and pancreatic adenocarcinoma (PAAD).