Inhibition of CD34⁺ colony formation by IK antisense oligonucleotides. CD34⁺ cells at 500/mL/dish were plated in semisolid media containing appropriate growth factors in the presence or absence of antisense/control oligonucleotides (10 μmol/L/mL). After 14 days of culture, colonies were scored. Results are expressed as a percentage of the control, ie, in the absence of oligonucleotide, for colony count (A) and colony size (B). The number of colonies obtained with the control culture were 10.3 ± 2.1 CFU-GEMM, 50.1 ± 9.1 iBFU-E, 21.2 ± 3.1 mBFU-E, 39.8 ± 5.9 large CFU-GM, and 70.0 ± 7.4 small CFU-GM. In control medium, the mean colony size was 16.1 ± 1.9 × 10³ cells. Student's t test for paired samples *P < .05, **P < .001 (n = 5).