DNA content of cultured splenic ECs and FISH analysis of ECs in spleen sections. (A) Representative example of DNA content analysis of JAK2V617F⁺ ECs obtained from in vitro culture of splenic mononuclear cells of patient number 6. Cells are 100% diploid. (B) Representative microphotograph of FISH analysis of ECs in a spleen section with a dual-color anti-JAK2 probe. Two cells, each with 2 green and 2 red signals (arrows), are shown.