IL6 and breast cancer: Control experiments measuring conditioned medium from chemically-injured murine stroma, from human breast cancer cells and from the two cell types cultured together using both murine and human cytokine antibodies demonstrates that IL-6 and IL-8 were produced almost entirely by the stromal cells when co-cultured with breast cancer cells (Fig. 9), suggesting that cancer cells induce further feedback injury to the stroma as they proliferate.