From the Human Protein Atlas (https://www.proteinatlas.org/), it was noted that HCN2 and HCN3 were found to be unfavourable prognostic markers of renal cancer, and strong cytoplasmic and membranous expression of HCN3 protein expression was observed in colorectal cancers and several other cases including breast cancer. This evidence concerns the gene HCN3 and breast cancer.