We selected SPC‐A1 cells for the TIMP‐3 silencing and tumor cell invasion assay because their endogenous TIMP‐3 level is lower than that of human lung fibroblast cells (HFL1) (Fig 3(a)), which is similar to TIMP‐3 expression in tumor cells from patients with lung cancer.9 This evidence concerns the gene TIMP3 and lung carcinoma.