MAPK11 and breast cancer: Furthermore, p38 MAPK was identified as a regulator of DKK-1 expression.23 In prostate cancer, p38 MAPK activity is also dysregulated and reports present both tumorigenic and tumor-suppressor roles.24, 25, 26, 27 In the context of malignant bone disease, MAPK11 in particular has been shown to augment osteoclastogenesis in breast cancer-induced bone resorption.28