Figure 4. SARS-CoV-2 S protein activates the NF-κB pathway.

(A, B) THP1 and A549 cells were stimulated with S2 (500 ng/ml) for indicated time points. Phosphorylation of P65, IκBα, ERK, JNK, STAT3, and AKT was measured by Western blotting. (C, D) THP1 cells were stimulated by SARS-CoV-2 S2 protein (500 ng/ml) in the presence or absence of IKKβ inhibitor sc514. Phosphorylation of P65 and IκBα was measured by Western blotting (C). The expression of IL6, IL1B, TNFA, CXCL1, and CXCL2 in stimulated THP1 cells was measured by real-time RT-PCR (D). Data represent mean ± SD (n=3); *p<0.05, **p<0.001, ***p<0.0001, ****p<0.00001 by unpaired Student’s t-test. Experiments in (A, B) were repeated three times and (C, D) were repeated two times. Data of representative experiments are presented.