Some genes such as MMP11 (extra-cellular matrix proteins), XRCC1 (DNA repair), VEGF (regulator of angiogenesis), Cyclin D1 (cell cycle regulators) and tumor-suppressor genes (Semaphorin 3B, WNT-5A) have been found as down-regulated genes during lung cancer progression (Campioni et al., 2008). Here, XRCC1 is linked to lung cancer.