As different tumour cells are differentially equipped with Sphk1 and Sphk2, those cells with high levels of Sphk1 have low Sphk2 levels, and vice versa, it may well be possible that in certain tumour or non-tumour cell types, hypoxia could also affect Sphk2 expression. The gene discussed is SPHK1; the disease is neoplasm.