Even though SK1 deficient (SK1-/-) [27] and MMTV-PyMT [28] mice have been available for more than 15 years, the generation of MMTV-PyMT SK1-/- mice to evaluate the effects of SK1 absence in spontaneous breast cancer development and metastasis has not yet been described. This evidence concerns the gene SPHK1 and breast carcinoma.