CXCR1 is expressed in non-NE tumor cells, not the NE tumor cells of PC. Adjacent sections from the prostate tissue microarray were prepared. A and B were adjacent sections from one core and C and D were adjacent sections from another core. The first sections (A, C) were stained with a monoclonal antibody for chromogranin A and the next sections (B, D) were stained with a monoclonal antibody for CXCR1. NE tumor cells (brown-stained cells in A and C, small arrows) are negative for CXCR1 (cells in B and D that do not show brown staining, small arrows). The non-NE tumor cells (cells in A and C that do not show brown staining, large arrows) are positive for CXCR1 (brown-stained cells in B and D, large arrows). Immunohistochemical staining. Original magnifications, ×400.