BAK1 and neoplasm: A variety of proteins, such as Bax, Bak, p53, Smac and TRAIL, are capable of inducing tumor cell apoptosis.[137] Among of them, TRAIL is a promising therapeutic protein, which selectively induces tumor cell apoptosis after binding to its cognate death receptors DR4 or DR5 expressed on tumor cell surface.[138] For example, Liu et al.