that lack of KREMEN1 would activate the Wnt/β-catenin pathway, thereby enhancing susceptibility to tumorigenesis55,56. Finally, NTN4 at 12q22 encodes a secreted growth factor that regulates tumor growth. High levels of NTN4 have been found in ER-positive but not ER-negative breast tumors57. NTN4 expression in tumors has also been suggested as a potential prognostic marker for breast cancer57.
