Under the cell culture conditions chosen (12-well plates, 80% confluency, 48 h, 500 μl volume of cell supernatant), Cxcl9+ cells secreted 57 pg/mL, whereas no Cxcl9 was detectable in the supernatants of Control cells (P = 0.0004; Fig. 1a), reflecting differentially CXCL9-expressing ovarian cancer cells (Supplementary Fig. S1A) or cancer microenvironments [12]. Here, CXCL9 is linked to ovarian cancer.