NTN1 and viral infectious disease: Various cell transfection or viral infection experiments have demonstrated that UNC5H or DCC, when expressed in the absence of netrin-1, can induce cell death, whereas the presence of netrin-1 is sufficient for blocking this proapoptotic activity (Mehlen et al, 1998; Forcet et al, 2001; Llambi et al, 2001; Liu et al, 2002; Tanikawa et al, 2003; Thiebault et al, 2003; Williams et al, 2003).