In order to investigate if radiation itself and/or respective cancer cells were able to activate fibroblasts into a pro-tumorigenic CAF phenotype, we quantified typical CAFs markers (α-SMA, PDGFR-β, and NG2) in mRNA isolates of NIH-3T3 and L929 fibroblasts after the indirect co-culture with cancer cells with or without radiation treatment using quantitative Real Time RT-PCR (qRT-PCR) (Figure 6). Here, PDGFRB is linked to cancer.