PRKD1 and prostate carcinoma: In this study we established a 3D prostate cancer epithelial-stromal interaction in alginate hydrogel microspheres by co-culturing prostate cancer C4-2 cells (stably transfected with Protein Kinase D1 (PKD1) or control vector) and normal prostate stromal cells (WPMY-1 cells) in the same microcapsule, but in separate sub-layers.