CXCR4 expression in primary cultures of feline mammary carcinoma. Upper panels. Representative immunofluorescence staining using anti-procollagen I (red) of fibroblast and purified feline mammary carcinoma primary cultures, after immunomagnetic fibroblast separation. DAPI-counterstained nuclei in blue. No fibroblast contamination is observed in the tumor cell cultures. Lower panel. A-B-C. Phase-contrast microscopy observation of the cultured cells derived from feline mammary gland tumours with an epithelioid morphology with some elongated spindle-shaped cells growing in monolayer (original magnification 10×) Panels D-E-F: immunofluorescence detection of CXCR4 expression (red) in primary cultures (DAPI-counterstained nuclei in blue). Original magnification 20×.