To test for a role of MAPK (mitogen-activated protein kinase) in PTER-ITC-induced PPARγ activation and apoptosis of breast cancer cells, we pre-treated MCF-7 and MDA-MB-231 cells with 20 μM ERK inhibitor (PD98059), 10 μM JNK inhibitor (SP600125) or 10 μM p38 MAPK inhibitor (SB203580) for 1 h, followed by PTER-ITC treatment for an additional 24 h. This evidence concerns the gene MAPK8 and breast cancer.