BUB1 and ovarian cancer: The genes VEGFA (vascular endothelial growth factor A), CALM1 (calmodulin 1), BIRC5 (baculoviral IAP repeat containing 5), POLD1 (polymerase-DNA directed, delta 1, catalytic subunit), AURKA (aurora kinase A), CDT1 (chromatin licensing and DNA replication factor 1), BUB1B (BUB1 mitotic checkpoint serine/threonine kinase B) with high connectivity degree > 30 were selected as the hub nodes and might play important roles in the progression of ovarian cancer.