SPHK1 and prostate cancer: Although autophagy induction by PF-543 has not been reported to date, other SphK inhibitors, the SphK1/SphK2 inhibitor SKI-II and the SphK2 inhibitor ABC 294640, have been shown to induce autophagy.29,30 McNaughton et al.31 reported that SKI-II and ABC 294640 inhibited DNA synthesis in androgen-independent LNCaP-AI prostate cancer cells, inducing proteosomal degradation of SphK1.