DUOXA1 overexpression elevates apoptosis signal-regulating kinase (ASK) 1 levels and induces apoptosis. (A-B) Cells were infected with pCMV5-GFP (GFP), or pCMV5-DUOXA1-GFP (GFP-DUOXA1). Twenty-four hours after infection, growth medium was replaced with differentiation medium and cells were harvested 24 hr later (day 1). (A) Apoptosis was measured by labelling samples with Annexin V-Cy3 (red) and propridium iodide (TOPRO-3 - magenta). Cells overexpressing DUOXA1 undergo massive amounts of apoptosis, as evidenced by cells undergoing early (Annexin V+/TOPRO-3-) and late (Annexin V+/TOPRO-3+) apoptosis. Scale bars: 100 μm. (B) Graphical representation of data presented in (A). Counterstaining with DAPI is provided as a nuclear marker. (C) Levels of ASK1 in GFP and GFP-DUOXA1 samples were analyzed by qRT-PCR. Samples were normalized to GAPDH and GFP-DUOXA1 values are displayed relative to GFP controls. Data suggest upregulation of ASK1 in samples overexpressing DUOXA1. * Significantly different from GFP control (P < 0.05).