There must be, however, some other factors affecting HAX-1 localization, since HAX-1-GFP-transfected MCF-7 breast cancer cells show nuclear localization of this fusion in about 21% of the analyzed cells (Additional Files 1 and 2), while estrogen treatment enhances nuclear localization only slightly, to about 26% (data not shown). The gene discussed is HAX1; the disease is breast carcinoma.