SPP1 and posterior cortical atrophy: Figure 6 showed the results of IHC for HSPC and mCRPC organoids with the SPP1-specific monoclonal antibody. Weak staining of SPP1 was observed in PCa organoids (Figures 6A,B), while the intensity of staining in mCRPC organoids was significantly stronger than in PCa organoids (Figures 6C,D).