Different from MCF‐7, MCF‐10A is a non‐tumourigenic and near‐normal mammary epithelial cell line.38 When we compared the expression ratio of matriptase/HAI‐1 in these two cell lines, we found that MCF‐7 had much higher ratio of matriptase/HAI‐1 than MCF‐10A (Figure 3B), which was consistent with the common concept that tumour cells have higher matriptase/HAI‐1 ratio.3, 4 The higher ratio of matriptase/HAI‐1 also led to the higher proteolytic activity of matriptase in MCF‐7 cells (Figure 3C). Here, SPINT1 is linked to neoplasm.