In order to evaluate whether GPER is involved in the angiogenic actions elicited by the IGF1 system in breast cancer, we analyzed gene expression from 17 published Affymetrix microarray tumor gene expression datasets of 2999 breast cancer patients [30] and METABRIC [29], a second independent dataset of 1973 breast tumor samples analysed for gene expression using Illumina BeadChips. Here, IGF1 is linked to breast cancer.