The inactivation of p110δ in MDA-MB-231-bearing tumour NSG mice (which have defective macrophages and lack T cells while their tumours express p110δ) or in 4T1-bearing tumour Balb/c mice (which have normal macrophages and normal T cells but their 4T1 tumours do not express p110δ) suppresses but is not able to entirely block tumour formation (Figs. 2d, e) pointing at an indispensable role of p110δ inactivation in both macrophages and cancer cells for breast tumour growth blockade. The gene discussed is PIK3CD; the disease is breast neoplasm.