SPP1 and prostate carcinoma: Then, in terms of the three main isoforms of OPN (OPN-a, OPN-b, and OPN-c), the angiogenic gene related to treatment resistance (VEGF-c), the gene expression of the EMT pathway (Snail and E-Cadherin), and prostate cancer biomarker (KLK2) were investigated with Real-Time PCR.