SPHK1 and triple-negative breast carcinoma: Patients with triple negative breast cancer have high cytoplasmic SK1 and S1PR4 levels, which was shown to be associated with shortened disease-specific survival and recurrence times, as well as more advanced lymph node status, suggesting a role for both SK1 and S1PR4 in metastasis and as important prognostic markers in triple negative breast cancer (73).