ST14 and breast cancer: Out of 16 breast cancer cell lines tested, seven did not express detectable levels of matriptase (∼44%; BT549, HBL100, MDA-MB-231, MDA-MB-157, MDA-MB-436, HS578T and HCC1569) and nine showed detectable expression of this protein (∼56%; ZR751, MCF7, MDA-MB-361, MDA-MB-453, BT474, MDA-MB-468, HCC1954, SKBR3 and T47D).