Contents of sphingenine (sphingosine) and sphinganine were studied in sphin
gomyelins of transplantable mouse tumors (hepatoma-22, melanoma B16, Lewis
lung carcinoma, intestine carcinoma) and rat nephroma RA. The content of sp
hinganine was increased in sphingomyelins of hepatoma-22 and nephroma RA co
mpared to sphingomyelins of liver and kidneys. Significant contents of sphi
nganine were also found in sphingomyelins of other studied tumors. The cont
ent of sphinganine in regenerating mouse liver (30 h after hepatectomy) was
normal. The data suggest that disorders should exist in biosynthesis of sp
hingoid bases in tumors but not in normal rapidly proliferating tissue.