SPHK1 and glioblastoma: In addition, down-regulation of SphK1 by specific siRNA or the specific inhibitor SK1-I (also referred to as BML-258) induces apoptosis and suppresses growth of human glioblastoma cells and xenografts by a process involving inhibition of protein kinase B (PKB, also known as Akt) and the activation of c-Jun N-terminal kinase (JNK) [194].