Fig 1: Levels of HP1 protein in breast cancer tissues are heterogeneous. A. Normal skin and breast tissues were stained with an anti-HP1ß antibody (upper panel). Representative examples of breast cancer sample staining by an anti-HP1ß antibody (lower panel). Depending on expression level and subcellular localization of HP1ß, cancer samples were classified to three groups. B. Comparison of expression HP1 subtypes in breast cancer samples. Three sets of 190 breast cancer tumors were stained with individual subtypes anti-HP1 antibodies, anti-HP1a, HP1ß or HP1? (Abcam antibodies: ab77256, ab10478, ab10480). IHC staining patterns were compared and IHC staining scores were determined as shown in S1 Fig. Scale bars: 100 µm. HP1-High indicates the group of tumors with abundant expression of all three HP1 subtypes. HP1-Low is the group with no or low expression of all three HP1 subtypes. HP1-Mixed group of cancer samples are high level expression with one or two HP1 subtypes. Representative images are shown.