Intracellular signaling pathways including Rac1/atypical PKC (aPKC)/S6K pathways and androgen signaling. An unknown molecule (X) downstream of androgen/androgen receptor (AR) may activate Rac1 and Src (depicted as dotted arrows) and may contribute to androgen-dependent cell proliferation. In castration-resistant prostate cancers, AR activity is upregulated by specific mutations for a promiscuous ligand-dependent manner or by other mechanisms, resulting in constitutive activation of Rac1/aPKC/S6K signaling through the same “X” or others.