In basal condition, C6 glioma cells expressed predominantly P2Y1 mRNA with lower levels of P2Y12 mRNA, but, when the cells were cultured in serum-free medium, the expression of P2Y1 mRNA decreased, whereas that of P2Y12 significantly increased (Czajkowski et al., 2004). The gene discussed is P2RY1; the disease is central nervous system cancer.