Ornithine decarboxylase, also known as ODC1, is the initial and rate-limiting enzyme in the biosynthetic pathway of polyamines and is involved in the conversion of ornithine to putrescine. ODC1 plays an important role in diverse biological processes, including cell growth, differentiation, transformation and apoptosis. Overexpression of the ODC1 gene plays important roles in cell proliferation and the development of cancer.