Effect of ST1926 on the levels of intracellular calcium in CD437-resistant NB4.437r blasts and other myeloid cell lines. Following prelodaing with the calcium fluorescent indicator FURA-2, NB4, NB4.437r, HL-60 KG1 (A) as well as Kasumi and U937 (B) cells (1 × 106/mL) were resuspended in PBS with calcium chloride at a concentr ation of 1.26 mM. Cells were placed in a cuvette under stirring at 37°C and changes in fluorescence were measured continuously with the use of a spectrophotofluorometer. The concentration of ST1926 used in the experiments illustrated in (A) and (B) is 1 μM. The dose-response curve for the increase of intracellular calcium in NB4 and NB4.437r cells is shown in panel C. Each tracing is representative of at least 2 independent experiments run in triplicate. *Significantly higher than the vehicle-treated group (P < .01 according to the Student t test).
