CD266 is a 14 kD transmembrane protein known as TWEAK receptor (TWEAK-R) or fibroblast growth factor inducible 14 (Fn14). It is member 12A of the tumor necrosis factor receptor superfamily (TNFRSF12A) expressed at low levels in a variety of tissues, such as heart, placenta, lung, muscle, and pancreas. TWEAK-R binds TWEAK (CD255) and interacts with the cytoplasmic proteins TRAF1, 2, and 3. The engagement of Fn14 can induce cell death and may play a role in inflammation, hepatocyte growth, and liver neoplasia.