In the present study, we used MDA-MB-468 triple negative breast cancer which overexpresses TMPRSS4 and MCF-7 triple positive breast cancer cell as a low expressed TMPRSS4 cancer cell (Li et al., 2017) and found that induction of TMPRSS4 expression down-regulation by using down-regulating TMPRSS4 vector inhibited cell proliferation compared to transfected control and the induction of TMPRSS4 up-regulation promotes cell proliferation which confirms the several above mentioned former studies results (Fan et al., 2018; Huang et al., 2014; Lee et al., 2016; Jung et al., 2008). The gene discussed is TMPRSS4; the disease is cancer.