Results showing that quiescent CML cells up-regulate IL-3 expression on entry into the cell cycle.

(A) The histograms show the level of proliferation by single, initially quiescent (G₀) CD34⁺ CML cells cultured for 4 days in SFM in the presence or absence of added growth factors. The results shown are the mean level of proliferation for 288 single G₀ cells analyzed from each of 3 similarly studied samples from patients with CML. (B) RT-PCR analyses of viable annexin-V⁻/PI⁻ populations of G₀or G₁/S/G₂/M CD34⁺ CML cells before (10 000 cells) and after (5000 cells) they were cultured for 4 days in either the absence (G₀⁻, G₁⁻) or presence (G₀⁺, G₁⁺) of added growth factors.