JNKs are a part of the superfamily of mitogen-activated protein kinases that heavily influence both cell proliferation and apoptosis, where the activation of JNKs can result in either proliferation or apoptosis, depending on the type of stimuli and/or cell type. One route through which JNKs influence extrinsic apoptosis initiation is through TNF interactions. Specifically, JNKs have been shown to be activated by TNFα, and JNKs can also contribute to TNF-induced apoptosis. JNK is also involved in intrinsic apoptosis initiation, where for instance, JNKs have been shown to induce the transcription of proapoptotic genes through direct transcriptional activity or through specific transcription factors, such as c-Jun. Additionally, JNK can mediate the expression of Bcl-2 family members. The JNK pathway therefore plays a large role in the regulation of both extrinsic and intrinsic apoptosis initiation pathways.