In vivo effect of pharmacologic inhibition of ERK-dependent hnRNP-E2 expression on neutrophilic maturation of differentiation-arrested myeloid 32D-BCR/ABL cells. H&E (top panels) and Leder (bottom panels) staining of the spleen sections of untreated and CI-1040–treated control and 6.15-MigRI and 6.15-WT-uORF cell–injected mice. In addition, all mice were cotreated with G-CSF. Microphotographs are representative of data obtained by analyzing multiples sections of spleens from 3 mice per group.