FAM3C also known as ILEI is a member of the family with sequence similarity 3 (FAM3) family and encodes a secreted protein with a GG domain. FAM3C plays a crucial role in studying cellular processes, particularly in cancer biology, as FAM3C is implicated in the epithelial to mesenchymal transition (EMT), a key event in tumor progression and metastasis. Elevated levels of FAM3C are observed in oncogenic Ras-transformed mammary epithelial cells, and FAM3C overexpression has been linked to the loss of tight junction protein ZO-1 and the expression of cytoplasmic E-cadherin, which together contribute to increased invasiveness and loss of cellular polarity. The interaction of ILEI with oncogenic Ras suggests a cooperative mechanism that drives TGFβ-independent EMT, making ILEI a significant factor in the invasion, metastasis, and survival of various cancers.