Recently, Hu et al conducted a comprehensive meta-analysis about five MMP polymorphisms and lung cancer susceptibility, and found that the MMP1-1607 1G/2G and MMP2-1306 C/T confer significantly susceptibility to lung cancer, and MMP1-1607’s effect was dependent on ethnicity, consistent with the results of this meta-analysis44. Here, MMP2 is linked to lung cancer.