DKK1 and prostate cancer: The bacterial antibiotic, anisomycin, is a potent activator of p38 MAPK42, 43 as shown by increased phosphorylation of p38 MAPK and HSP27 a specific downstream target.44, 45 In the prostate cancer cell lines investigated, this resulted in a potent increase of DKK-1 mRNA expression, most apparent in the osteolytic PC3 cells.