CSF1R expression in canine mammary cancer cell lines in control conditions and after the co-culture with macrophages. (A) The graph of mean optical density of CSF1R (and SD) in canine mammary cell lines (CMT-U27, CMT-U309, P114, CMT-W1 and CMT-W2) grown in control conditions (ctrl) and as a co-culture with macrophages (+MQ). (B) Representative pictures of CSF1R expression in CMT-W2 cell line (in control conditions and after co-culture with macrophages) obtained using Olympus BX60 microscope (at the magnification of 200×). The CSF1R is reflected as brown colour. Ten pictures in each slide were analyzed. The colorimetric intensity of the IHC-stained antigen spots was counted by a computer-assisted image analyzer (Olympus Microimage™ Image Analysis, software version 4.0 for Windows, USA) and the antigen spot colour intensity is expressed as mean pixel optical density on a 1-256 scale. The statistical analysis was performed using Prism version 5.00 software (GraphPad Software, USA). The unpaired t-test was applied to analyze the optical density in cell lines. p < 0.05 was regarded as significant and marked as *.