NSC606985 induces proteolytic cleavage of PKCδ proteins in NB4 and U937 cells. (A) NB4 and U937 cells were treated with or without 25 nM and 50 nM NSC606985, respectively, for the indicated times. PKCδ proteins were detected by Western blots with β-actin as an internal control. Molecular weights (MWs) of standard protein markers were indicated. ΔPKCδ indicates cleaved 41-kDa catalytic fragment of PKCδ proteins. (B) NB4 cells were treated with 25 nM NSC606985 for 12 hours, and U937 cells were treated with 50 nM NSC606985 for 36 hours. Nuclear and cytoplasmic proteins were extracted and subjected to Western blotting for the detection of PKCδ proteins. Lamin B was used as a nuclear protein control.