Immunofluorescence analysis showed many α-smooth muscle actin (α-SMA)-positive fibroblasts and fewer CD8-positive T cells in 4T1 breast tumors, especially in pimonidazole-positive ( a probe for tumor hypoxia ) hypoxic regions (Fig. 3c and Additional file 1: Figure S7 ). The gene discussed is CD8A; the disease is breast neoplasm.