Using qPCR, we observed fibroblasts had a c-kit receptor that changed the expression level under different conditions. Figure 5a shows c-kit gene expression was increased with UVB stimulation, even under SCF gene silencing by siRNA transfection compared with regular fibroblasts. In an attempt to demonstrate the existence of an autocrine system in fibroblast cells, different tests were conducted. In Figure 5b, the fibroblast’s inner SCF levels were downregulated when treated with 30 ng of recombinant SCF, while the fibroblast’s inner SCF levels were upregulated when treated with 3 µM of masitinib, which is an inhibitor of SCF and c-kit. When combined, 30 ng of SCF and 3 µM of masitinib produced a result similar to the controlled fibroblast’s inner SCF level. When treated with inhibiting or facilitative SCF environments, fibroblast cells varied their inner SCF levels to balance out their inner and outer levels, confirming the existence of an autocrine signaling system.