As the various growth factors secreted from cancer cells and surrounding stromal cells may regulate cancer cell proliferation in the tumor microenvironment, we examined whether growth factors including EGF, HGF, PDGFα, NGF, TGF-β, and insulin, and several cytokines such as IL-2, IL-6, and LPS, can induce Crk expression. The gene discussed is IL6; the disease is cancer.