LIV-1 is expressed as two isoforms. LIV-1 is a multi-pass cell membrane protein that is 749 amino acids in length and is expressed abundantly in breast, prostate, placenta, kidney, pituitary and corpus callosum, as well as in cells derived from various types of cancers affecting the glands, cervix and lungs. LIV-1 is a member of the ZIP transporter protein family which consists of 14 members that transport zinc. LIV-1 transports zinc from its position on the plasma membrane into the cytosol of the cell and contains a histidine-rich transmembrane domain which is thought to bind zinc and aid in its transportation. LIV-1 is thought to be important for zinc uptake in neuroblastoma cells and may also be crucial for maintaining zinc homeostasis, a process which aids in the prevention of cancer and disease. Activated estrogen receptors are thought to regulate LIV-1 expression at the level of transcription, via the mRNA precursor to LIV-1 which associates with estrogen receptors that are activated by growth factors and estradiol. LIV-1 is upregulated in hormone-rich tissue, including breast and cervical cancer, where it is thought to affect cell motility and may play an important role in tumor development and metastasis. Conversely, less aggressive tumors may contain high levels of LIV-1 that could lead to apoptosis, indicating a dual role for LIV-1 in tumor suppression.