HSPB8 and pachyonychia congenita: In fact, in some tumors, HSPB8 promotes tumor growth (e.g., in BC [77,87], lung cancer [88], multiple myeloma [89], ovarian cancer [90], and gastric cancer [91,92]), while in other tumors (e.g., in melanoma [41,93,94], leukemia [39,40,92,95], glioblastoma [69,96], hepatocarcinoma [97,98,99], and prostate cancer (PC) [40,100,101,102]), HSPB8 has the opposite effect and reduces tumorigenesis (Figure 4).