The nuclear receptor small heterodimer partner (SHP, Nr0b2) was originally identified in 1996 as a transcriptional repressor based on its protein-protein interactions with several nuclear receptor superfamily members such as retinoid receptors, the thyroid hormone receptor, and the orphan receptor MB67 (Seol et al. 1996). The SHP gene consists of two exons and one intron located at human chromosome 1p36.11, mouse chromosome 4 D2.3, and rat chromosome 5q36. Since no endogenous ligand for SHP has been identified so for, SHP is classified as an orphan nuclear receptor. However, SHP is present in a variety of tissues. In mice, SHP is abundant in the gallbladder and liver while expressed at lower levels in the brainstem, cerebellum, adrenal, pancreas, stomach, duodenum, jejunum, ileum, colon, kidney, ovary, testis, and heart. In humans, SHP expression is detectable in the...