GRP and pachyonychia congenita: Immunohistochemical (IHC) staining of Ki67 (proliferation marker), nuclear p65-pho and AR-V7 further confirmed that activation of GRP/GRP-R signaling supports androgen dependent PC tumors to continue to grow in the castrated mice by elevating NF-κB activity and AR-V7 expression in PC cells (Figure 4B and 4C).