The frequent mutation of the JNK pathway in human breast cancer (including the genes MAP3K1, MAP2K4, and MAP2K7) implicates reduced JNK signaling in the etiology of mammary carcinoma (Banerji et al., 2012; Cancer Genome Atlas Network, 2012; Ciriello et al., 2015; Ellis et al., 2012; Kan et al., 2010; Nik-Zainal et al., 2016; Shah et al., 2012; Stephens et al., 2012; Wang et al., 2014). This evidence concerns the gene MAPK8 and breast cancer.