As a master regulator in hypoxic cancer progression, HIF-1α activates transcription of many genes23, two publications of microarray hybridization analysis have reported that PTGIS is an important target gene of HIF-1α28,44, and our microarray analysis (GEO accession no. GSE76211) indicate that PTGIS is a significantly downregulated gene in BCa tissues compared with normal bladder tissues. This evidence concerns the gene HIF1A and cancer.