Characterization of UM-PEL-3 cells. (A) Pathological findings for the UM-PEL-3 xenograft mouse model. (I-II) Hematoxylin and eosin-stained tissue sections of the gastrointestinal tract showing extensive infiltration of the muscularis propria by lymphoma cells. (II) Higher magnification of pleomorphic lymphoma cells with hyperchromatic nuclei. (III) Immunohistochemistry for CD138 and (IV) HHV8 latent antigen LANA. Original magnification ×400 (I) and ×600 (II-IV). (B) IFA of UM-PEL-3 cells reveals positive staining for HHV8 latent antigen LANA (red). (C) UM-PEL-3 cells were stimulated with 1 mM butyrate for 4 days and RNA expression of the indicated transcripts was measured by qRT-PCR. Fold change compared with unstimulated cells indicates induction of IE (RTA), early (ORF55), or late (gB and K8.1) lytic genes. Error bars correspond to standard error of mean. (D) Immunostaining image of late lytic protein K8.1 (red) in UM-PEL-3 cells stimulated with 0.75 µM SAHA for 24 hours (bottom) and unstimulated cells (top). For panels B and D, nuclei are stained with 4,6 diamidino-2-phenylindole (DAPI; blue). Magnification ×400. Experiments depicted in panels B-D were repeated thrice independently in triplicate. The representative data from one experiment are shown.