Figure 4.

PPM1D suppresses p38 MAPK and p53 signaling pathways. p-p38 MAPK, p53 and Bax protein levels were upregulated in siPPM1D-treated thyroid cancer cells. (A and B) Western blot analysis of protein levels in TPC-1 and K-1 cells transfected with siPPM1Ds or scrambled RNA for 24 h (upper panel) and relative quantitative analysis of the protein levels in each group (lower panel). Values are expressed as the mean ± SEM of three independent experiments. P-values were determined using ANOVA test followed by Tukey's post hoc test. *P<0.05, **P<0.01, ***P<0.001. N.S., no significance; PPM1D, protein phosphatase, Mg²⁺/Mn²⁺ dependent, 1D; p-p38, phosphorylated p38; MAPK mitogen-activated protein kinase; WT, wild-type; NC, negative control; siPPM1D-1/siPPM1D-2: siRNAs against PPM1D; siRNA, small interfering RNA.