Molecular analyses of

PLZF-RARα cases. (A) Case 52 with a normal karyotype and formation of PLZF-RARα as the sole fusion gene due to an insertion event. FISH using ICRF RARα 121 (green) cosmid probe and chromosome 11 centromeric probe (red) demonstrated insertion of RARα sequences into band 11q23. (B) RT-PCR revealed expression of PLZF-RARα (3ZFPLZF breakpoint) as the sole fusion transcript in case 52, whereas both fusion transcripts were detected in cases 46 (2ZF) and 53 (3ZF). (C,D) PML immunofluorescence using the PG-M3 antibody on cytospin preparations from case 43 (C) and case 52 (D, courtesy of Francesco Fazi) showed a wild-type pattern, as distinct from the microparticulate PML staining shown in NB4 cells in Figure 8. Images were captured on a Zeiss Axioplan fluorescence microscope.