Loss of PTPN22 enhances p38 and JNK MAPK phosphorylation.

<p><b>A–D:</b> THP-1 cells, expressing either non-targeting control shRNA or PTPN22 targeting shRNA, were treated for 30 min. with 500 ng/ml MDP. Representative Western blots and respective densitometric analysis show levels of (<b>A</b>) PTPN22 and β-actin; (<b>B</b>) phospho-p38 (Thr¹⁸⁰/Tyr¹⁸²) and total p38; (<b>C</b>) phospho-JNK (Thr¹⁸³/Tyr¹⁸⁵) and total JNK; (<b>D</b>) phospho-ERK (Tyr⁴²/Tyr⁴⁴) and total ERK. (<b>E+F</b>) BMDC from either wild type (WT) or PTPN22 knockout (PTPN22.KO) mice were stimulated for 30 min with 500 ng/ml MDP. Representative Western blots and densitometric analysis below show levels of (<b>E</b>) phospho-p38 (Thr¹⁸⁰/Tyr¹⁸²) and total p38; and (<b>F</b>) phospho-ERK (Tyr⁴²/Tyr⁴⁴) and total ERK. Asterisks denote significant differences from the respective control (n = 3 each, * = p<0.05, ** = p<0.01, *** = p<0.001); # = p<0.05, # = p<0.01, ### = p<0.001 <i>vs.</i> MDP-treatment of cells expressing control shRNA.