(A) VCaP cells were transfected with control, INPP4B, or PTEN specific siRNAs. Expression levels of INPP4B, PTEN, pPKCζ, pPKCβII and β-tubulin were measured by Western blotting. (B) LNCaP cells were transfected with control or INPP4B siRNAs for 48 hours in medium supplemented with 10% FBS. Cellular lysates were assayed for INPP4B, pAkt, pPKCζ, pPKCβII and β-tubulin by Western blotting. (C) C4–2 cells were transfected and assayed in parallel with B. (D) LNCaP cells were plated in complete medium and treated with indicated inhibitors for 8 hours. Protein extracts were assayed for AR, INPP4B, pS6, and tubulin levels by Western blotting. (E-J) LNCaP cells were plated in medium supplemented with 10% CSS with either vehicle or 1 nM R1881. Twenty four hours later cells were treated with vehicle (DMSO), 5μM AZD5363, or 2 μM BIM-I for an additional 8 hours. In parallel, LNCaP cells were transfected with control or INPP4B siRNA for 48 hours in 10% CSS medium supplemented with 1 nM R1881. RNA was purified, reverse transcribed, and expression levels of AR regulated genes PLA2G2A (E), KIAA1324 (F), TARP (G), NNMT (H), TMPRSS2 (I) and SYTL2 (J) compared by RT-qPCR. ** represents p < 0.01; *** represents p < 0.001.