Brizuela et al. [40] reported, for the first time, that green tea polyphenols (EGCG and polyphenon E, PPE) inhibit SphK1 activity, via a novel ERK/PLD-dependent mechanism in prostate cancer cells (C4-2B hormone-responsive and PC-3 hormone-refractory). This evidence concerns the gene SPHK1 and prostate cancer.