Sphingosine kinase 1 expression is downregulated during differentiation of Friend cells due to decreased c-MYB

► SPHK1 but not SPHK2 was overexpressed in a mouse Friend erythroeukemia cell line. ► SPHK1 expression of Friend cells affects their proliferation and differentiation. ► SPHK1 expression decreased during HMBA-induced differentiation. ► 5′-promoter between − 53 bp and the first exon is important for SPHK1 transcription. ► C-MYB regulates SPHK1 transcription by its binding with the 5′-promoter region.