Expression of FSHR in invasive breast cancer as function of molecular subtype of tumors. Immunofluorescence confocal microscopy analysis was performed on paraffin-embedded sections of human breast cancer tissues with the use of the anti-FSHR monoclonal antibody 323, followed by a red-labeled secondary antibody. Irrespective of molecular subtype, breast tumors showed strong staining of blood vessels (A through D). Anti-HER2 and anti-ER antibodies, followed by a green-labeled secondary antibody, confirmed the molecular subtype of breast tumors. Green signals from rabbit antibodies against HER2 (A and C) and estrogen receptor (B) were merged with the red signal from the anti-FSHR antibody. Sections were also stained with DAPI (C and D). (A,B) HR+/HER+ breast tumors. Please note that tumor cells with strong signal for HER2 (asterisk) did not express the estrogen receptor. C) HR-/HER2+ tumors; D) triple negative tumors. The scale bar represents 20 μm in all panels.