This is from the same experiment as in Figure 4. Female NOD-SCID mice xenotransplanted with MV4;11 cells were randomly assigned to receive daily IP injections of 20 mg/kg I-BET151 or vehicle control after detection of disease. Tissues containing observed tumors were fixed, sectioned, and stained with an antibody against human leukocyte antigen (HLA-A,B,C) and counterstained with hematoxylin. (A) Positive control staining of human tonsil tissue that was processed in parallel with other tissue sections (magnification: 400X left, 100X right). Representative images of various tissues from MV4;11 engrafted mice who received vehicle treatment, which include (B) stomach (magnification: 400X left, 100X right), (C) gastrointestinal tract (magnification: 400X left, 100X right), (D) mesentery (magnification: 400X left, 20X right), (E) ovary (magnification: 400X left, 20X right), and (F) peritoneal cavity (magnification: 400X). Mouse tissues (e.g. gastrointestinal mucosa) were negatively stained. Additional details for this experiment can be found at https://osf.io/jakpw/.