NOD/SCID mice transplanted with BCR/FGFR1- and ZMYM2/FGFR1-expressing cells display BM fibrosis. (A) Reticulin-stained BM sections from a representative BCR/FGFR1 mouse and a ZMYM2/FGFR1 mouse reveal pronounced fibrosis, whereas all MIG mice displayed normal reticulin. (B) Two representative megakaryocytes from BCR/FGFR1 mouse BM shown to be of murine origin as determined by FISH analysis (red signals, murine cells; green signals, human cells).