KLF4 and prostate cancer: For validating this prediction, we selected a set of prostate cancer stem cell-specific genes: BMI-1, NKX3.1 and SOX-4; mesenchymal stem cell-related COL1A1; and critical regulators of pluripotent embryonic stem cells (ESC): KLF-4, SOX-2, OCT-4 and NANOG. [23–26] The qPCR analysis of total RNA samples isolated from cultured LNCaP-TLR9 variants or in vivo grown LN-TLR9HI and LN-TLR9LO tumors showed the significant upregulation of majority of the tested stem cell-related genes after TLR9 expression (Figure 2A, top/middle).