Macrophages are well known to be able to stimulate the invasion process and metastasis of cancer cells, partly through inducing the expression of MMP‐9 which leads to matrix remodeling.1 In order to fully explore the underlying mechanism by which Six1 expression in macrophages affects the invasiveness of HA59T cells, we examined MMP‐9 expression level in macrophages having different levels of Six1 expression. This evidence concerns the gene MMP9 and cancer.