FISH analysis of IL-7LN⁺ cells from patient no. 2 with a translocation t(9:11) and the respective MLL/AF9 gene fusion.

IL-7LN-transduced and sorted cells were hybridized with probes that flank the MLL breakpoint and were counterstained with DAPI. The MLL5′ probe is labeled with FITC (green signal) and the MLL3′ probe with CY3 (red signal). The colocalized signals define the normal allele, whereas the separated red and green signals represent the translocated allele.