Its potential as a tumour suppressor was tested in breast and gynaecological cancer models, based on observations that its locus is deleted or its expression downregulated in basal‐like breast cancer and gynaecological cancers; in these cases, OIP5‐AS1 phenocopied PTEN effects in breast, endometrial and ovarian cancer cells, and broadly regulated other master cancer regulators.117. The gene discussed is OIP5; the disease is cancer.