Expression of herg1, flt-1 and kdr transcripts in peripheral blasts from AML patients. (A) Representative RT-PCR of herg1 (upper panel, 575-bp band), flt-1 (upper middle panel, 550-bp band), kdr (lower middle panel, 660-bp band), and gapdh (bottom panel, 138-bp band) transcripts in primary AML patients. RNA extracted from blasts of AML patients was retrotranscribed and amplified for herg1, flt-1, kdr, and gapdh using primers described in “Patients, materials, and methods; Molecular biologic methods.” For case reference numbers, see Table 1. (B) Immunocytochemistry detection of hERG1 and FLT-1 protein on AML blasts. Cells from a representative AML example relating to case A49 were immunostained with an anti-pan hERG1 antibody (left) and anti FLT-1 antibody (right) as reported in “Patients, materials, and methods; Immunohistochemistry” (100× magnification). Images were acquired on a Leica DM 4000B microscope with a Leica DFC 320 photocamera (Leica Microsystems) (PL Fluotar 40×/0.70, PL Fluotar 100×/1.30 OIL objective). To determine BM angiogenesis, BM sections were stained with anti-CD34 antibodies. Vascular morphometric parameters were quantified following the procedure used by Korkolopoulou et al,³⁰  with Leica DC Viewer software.