According to previous reports, in addition to its expression in tumor tissues, Plac1 is also highly expressed in the placenta and is downregulated during embryonic development and maturation.[29] The process by which Plac1 expression is downregulated during embryogenesis is exactly the opposite of that by which Plac1 is upregulated during tumor initiation and progression. This evidence concerns the gene PLAC1 and neoplasm.