(A-C) The effect of PLK1 siRNA on PLK1 expression. THP-1 cells, transfected with PLK1 siRNA as described in Materials and Methods, were untreated (A) or stimulated with 1 µg/ml Pam3CSK4 (P3C4) for 1 h (B-C). The protein expression of PLK1 was detected by western blot (A, C). The gene expression of PLK1 was detected by qRT-PCR (B). * P < 0.05 compared with the non-treated groups. (D) PLK1 RNA interference down-regulated cytokine transcript expression. THP-1 cells, transfected with PLK1 siRNA, were stimulated with 1 µg/ml Pam3CSK4 (P3C4) for 1 h. The transcript expression of TNF-α, IL-1β, and IL-8 were detected by qRT-PCR. * P < 0.05 compared with the non-treated group. (E) The effect of PLK1 siRNA on cytokine protein expression. THP-1 cells, transfected with PLK1 siRNA, were stimulated with 1 µg/ml Pam3CSK4 (P3C4) for 24 h. The protein expression of TNF-α and IL-8 was detected by ELISA. * P < 0.05 compared with the Pam3CSK4-treated alone group.