It also must be pointed out that transcriptional induction of p21Cip1 and p27Kip1 mRNA by SphK inhibitor in mesothelioma cells did not translate to increased protein levels (Fig. 9) thereby questioning the importance of CDK inhibitors in SphK1 mediated signaling in mesothelioma cells. Here, SPHK1 is linked to mesothelioma.