ST14 and breast cancer: Nevertheless, in human T-47D human breast cancer cells, induction of matriptase activation by exposure to pH 6.0 buffer resulted in the formation of three HAI-2 complexes of 100-, 120-, and 130-kDa along with the formation of the 120-kDa matriptase-HAI-1 complex (Fig. 3B, comparing lanes 2 with lanes 1).