Compared with the control group, mice harboring RIPK2-KO 22Rv1 cells showed substantially lower metastatic burden (84% reduction at week 4) (Fig. 2h, i and Supplementary Fig. 6a, b), longer bone metastasis-free survival (Fig. 2j), and less weight loss (Supplementary Fig. 6c), suggesting that RIPK2 is critical for PC metastasis. This evidence concerns the gene RIPK2 and pachyonychia congenita.