Co-inmunofluorescence analysis of HIF-1α and MCT4 showed that although, in some tumor areas, both proteins were co-expressed in the same tumor cells, this overlapping was imperfect; tumor areas containing MCT4 positive cells and complete absence of HIF-1α positive nuclei in and around MCT4 positive cells were frequently detected (Figure 4). The gene discussed is HIF1A; the disease is neoplasm.