The different subcellular localizations of HAI-1 and HAI-2 result in the ability of HAI-1 but not HAI-2 to control matriptase activity in mammary epithelial cells.

<p>Human mammary epithelial cells 184 A1N4 were exposed to fresh culture medium for 30 min to induce matriptase zymogen activation. The non-activation control (<i>A, C</i>, and <i>E</i>, red) and the treated cells (<i>B, D</i>, and <i>F</i>, red) were subjected to indirect immunofluorescent staining using the total matriptase mAb M24 (<i>A</i> and <i>B</i>, red), the activated matriptase mAb M69 (<i>C</i> and <i>D</i>, red), and HAI-2 mAb DC16 (<i>E</i> and <i>F</i>). The cells were also counterstained with Alexa Fluor 488 labeled phalloidin for F-actin (green) and DAPI for nuclei (blue). Merged images are presented in <i>A’, B’,C’, D’, E’ and F’</i>. Scale bar: 10 μm.