Sensitivity to pan-JAK inhibitor CMP6 of GF-independent and CMP6-selected TS1 clones. (A-B) GF-independent TS1 clones with endogenous JAK1 or JAK3 mutants and CMP6-selected TS1 clones with endogenous JAK1 and JAK3 mutants were seeded in 96-well plates at a density of 1000 cells/well with increasing concentrations of pan-JAK inhibitor CMP6 (0 to 1 μM). After 48 hours, methyl-³H thymidine was added to the cells for 4 hours and thymidine incorporation was measured. Results are means ± standard deviation of triplicate cultures represented in % of control untreated cells.