To verify that Fmrp levels affect tumour progression, we used two murine breast cancer cell lines with different metastatic properties, 4T1 (Tao et al, 2008) and TS/A (Nanni et al, 1983), and with different levels of Fmrp expression (Fig 2A and Supporting Information Fig S3). The gene discussed is FMR1; the disease is neoplasm.