UL33 and UL78 modulate calcium mobilization in response to CCL5 and decrease CXCL12-induced IP production in THP-1 cells. (A-C) IP production after stimulation with increasing concentrations of CCL5 (A) or CXCL12 (C) was assessed in THP-1 cells expressing mock (closed squares), Flag-UL33-YFP (closed circles), or Flag-UL78-YFP (closed triangles). (B-D) Average peak Ca²⁺ concentrations triggered by 100nM CCL5 in HA-CCR5 transfected THP-1 cells (B) or by 10nM CXCL12 in THP-1 cells (D) coexpressing mock, Flag-UL33 or Flag-UL78. Mock = pcDNA3 expression vector. Statistical differences of calcium concentrations or maximal IP1 production compared with mock nucleofected cells were assessed using the Student t test (*P < .05; **P < .01; ***P < .001).