The lipocalin 24p3, which is an essential molecule in IL-3 withdrawal-induced apoptosis, is not involved in the G-CSF withdrawal-induced apoptosis

: Many hematopoietic cells undergo apoptosis when deprived of specific cytokines. Lipocalin 24p3, reported to be induced in hematopoietic cells by interleukin 3 (IL‐3) depletion, induces hematopoietic cell apoptosis despite the presence of IL‐3. As granulocyte colony stimulating factor (G‐CSF) depletion also induces the apoptosis of G‐CSF‐dependent cell line cells, we examined the effect of 24p3 on the apoptotic function induced by G‐CSF depletion. 24p3 was induced by the depletion of IL‐3, but not G‐CSF, in cytokine‐dependent cell lines. Although 24p3 suppressed growth induced by IL‐3, it did not influence G‐CSF‐dependent cell growth. These observations show that 24p3 is not involved in the G‐CSF withdrawal‐induced apoptosis, although it is essential in IL‐3 withdrawal‐induced apoptosis.