Protein LDOC1 contains a leucine zipper-like motif and a proline-rich region that shares marked similarity with an SH3-binding domain. The protein localizes to the nucleus and is down-regulated in some cancer cell lines. It is thought to regulate the transcriptional response mediated by the nuclear factor kappa B (NF-kappaB). The gene has been proposed as a tumor suppressor gene whose protein product may have an important role in the development and/or progression of some cancers.

LDOC1 was expressed in 6 of 7 human breast cancer cell lines examined, but, with only 1 exception, was not expressed in any pancreatic or gastric cancer cell lines examined. Fluorescence microscopy analysis demonstrated that the LDOC1 protein is located predominantly in the nucleus.