Angioproliferative lesions in RCAS-racQL–injected TIE2-tva mice closely resemble early vGPCR experimental KS lesions. (A) Immunofluorescence of permissive (DF1) chicken fibroblasts infected with RCAS alone (control), RCAS-GFP, RCAS-vGPCR, or RCAS-racQL virus, respectively. Expression of vGPCR or RacQL was detected by staining against AU5 or hemagglutinin (HA) tags, respectively. (B) Representative vascular lesions found in liver from 2 TIE2-tva mice injected with RCAS-racQL (10⁷ IU). Liver from a littermate control injected with RCAS-GFP showed no lesions. Scale bar, 5 mm. (C) Representative hematoxylin and eosin (H&E) staining of liver reveals benign angiectasias similar to those seen in early vGPCR experimental KS lesions. Sections initially photographed at magnification × 40. Scale bar, 50 μm.