Oxidoreductase required for tumor suppression. NAPDH-bound form inhibits nuclear import by competing with nuclear import substrates for binding to a subset of nuclear transport receptors. May act as a redox sensor linked to transcription through regulation of nuclear import. Isoform 1 is a metastasis suppressor with proapoptotic as well as antiangiogenic properties. Isoform 2 has an antiapoptotic effect.
Ubiquitous. Highest level in liver. High levels in lung, skeletal muscle, pancreas and placenta. Moderate levels in heart and kidney. Low levels in brain. Not expressed or low levels in variant small cell lung carcinomas, 33% of hepatocellular carcinomas and neuroblastomas.
Unique C-terminus confers high proteasome-dependent instability to isoform 2.