MAPK8 and Obesity: To further determine the specific MAPK pathways involved in MKP-5-mediated regulation of islet cell apoptosis and dysfunction in the context of obesity, we pretreated Rin-m5f cells with SP600125 (JNK inhibitor), SB203580 (P38 inhibitor), or U0126 (ERK inhibitor) for 1 h, which was followed by transfection with si-MKP-5 or si-SC and PA exposure.