Differential effects of Walker 256 carcinosarcoma cells growing subcutaneously, intramuscularly, or intraperitoneally on hepatic microsomal mixed-function oxygenase activity.

Walker 256 rat carcinosarcoma cells growing as solid subcutaneous or intramuscular tumors depressed hepatic microsomal mixed-function oxygenase activity to less than 20% of control activity, but the same tumor cells growing as free ascites cells in the peritoneal cavity did not. Necrosis of the core area of solid tumors was observed. Tumor cells may release a substance that depresses hepatic microsomal mixed-function oxygenase activity only upon their death.