Further supporting a role for SphK1 in promoting cancer, SphK1 has been found to act as an oncogene [28], its mRNA is overexpressed and positive immunostaining for SphK1 was found in various tumors [29], [30], [31], [32], [33], and the increase in SphK1 expression in tumor biopsies was correlated with short survival rate in patients with glioblastoma and breast cancers [30], [34]. This evidence concerns the gene SPHK1 and breast cancer.