Previous reports show 4T1 tumour cells induce profound granulocytosis in vivo [9, 21] and separate reports reveal a critical role for G-CSF in 4T1 growth and metastasis through changes in granulocyte frequencies (referred to in those reports as myeloid-derived suppressor cells, MDSCs, which can have a CD11b+Ly6G+ phenotype) [22]. The gene discussed is CSF3; the disease is Increased total granulocyte count.