(A) HL60 cells were electroporated with the βRARE-tk-Luc reporter (25 μg) together with expression vectors (20 μg) harboring WT or constitutively activated (ca) CaMKII cDNAs (CaMKIIα). ATRA (1 μM) was added, and relative luciferase activity determined after 6 hours. (B) HL60 cells were stably transduced with empty (control) retroviral vectors and with vectors harboring CaMKIIγ shRNAs as detailed in Methods. Western blotting identified 6 CaMKIIγ shRNA–transduced HL60 subclones (A6, B2, B5, B6, C2, and C18) with reduced CaMKIIγ protein expression. (C) Pooled subclones of the CaMKIIγ shRNA vector–transduced HL60 cells that exhibited reduced CaMKIIγ expression on Western blots (B) together with control (empty) vector–transduced HL60 cells were lysed and immunoprecipitated with CaMKIIγ antibody; the immunoprecipitates were assayed for both Ca²⁺/CaM–independent (EGTA) and Ca²⁺/CaM–dependent (Ca²⁺/CaM) enzyme activity. (D) Pooled subclones described in C that exhibited reduced CaMKIIγ expression/activity (B and C) as well as control (empty) vector–transduced cells were electroporated with the βRARE-tk-Luc reporter (25 μg), and relative luciferase activity was determined as described above. (E) The subclones described in C that exhibited reduced CaMKIIγ expression/activity (B and C) as well as control vector–transduced cells were treated with RA (1 nM) for 5 days followed by FACS quantitation of Cd11b surface antigen. (F) HL60 cells were electroporated with the βRARE-tk-Luc reporter (25 μg) together with a control empty vector or a vector harboring the CaMKII-inhibitory protein (CaMKIINα), and relative luciferase activity determined as described above.