SMPD1 and breast cancer: Five different cell types were included in experiments, namely human umbilical vein endothelial cells (HUVEC), acute myeloid leukemia cells (AML), murine fibrosarcoma cells (KHT-C), prostate cancer cells (PC3), breast cancer cells (MDA-MB-231), and astrocytes (ASMase +/+) and (ASMase −/−).