Shp2 antisense oligonucleotides induce growth inhibition and apoptosis of leukemic clonogenic growth. (A) Leukemic cells were plated in 24-well culture plates in 0.5% soft agar with different concentrations of Shp2-specific antisense oligonucleotide (▪) for 7 days, and then colonies (> 40 cells) were counted using an inverted microscope. Each experiment was performed at least 3 times. Note: The sense oligonucleotide of Shp2 (□) was also found to have a modest growth inhibition on leukemic colonies at high concentrations. (B) Microphotographs of leukemic colonies after exposure to antisense (i, iii) and sense (ii, iv) oligonucleotides at 2 μM for 72 hours. Images were viewed at 400 ×/0.75 NA, with a Zeiss Axioskop II microscope. Images were captured with a SPOT 1.3.0 CCD camera and transferred to Adobe Photoshop 6.0. (C) Leukemia cells were cultured in RPMI-1640 with 10% serum, treated with different doses (0 μM-4 μM) of Shp2-specific antisense oligonucleotides for 72 hours, and then collected for analysis of Shp2 expression by Western blot, and apoptosis with FCM. Data are representative of 3 independent experiments with standard error.