SPHK1 and prostate carcinoma: revealed that lipopolysaccharide (LPS), the main component in the membrane of Gram-negative bacteria, could activate SphK1 by inducing the S225 phosphorylation of SphK1 and its translocation to the plasma membrane, resulting in S1P production and S1PR4 receptor activation which enhances invasion and metastasis of prostate cancer cells [71].