TENT5C and Miyoshi myopathy: Given that, among the two known SphK isoforms (i.e., SphK1 and SphK2), SphK1 is more prominently involved in cancer progression while SphK2 has less defined and context-dependent effects [20], we decided to test the efficacy of specifically targeting Sphk1 in MM cell lines harboring different levels of FAM46C.