siRNA knockdown of MMP9 in OVCA433 significantly reduced OVCA433 proliferation in co-culture (Figure 7A and Supplementary Figure S3C), suggesting that MMP-9 secreted by OVCA433 during co-culture feeds back to the THP-1 to release HB-EGF and drive tumor cell proliferation. The gene discussed is GSTM1; the disease is neoplasm.