FOS and neoplasm: In the search for experimental paradigms including the complex environment in which in vivo tumor development occurs, herein we examined the status of cytoplasmic c-Fos expression and phospholipid synthesis activation in malignant human brain tumors, in the NPcis mouse -an animal model of the human disease Neurofibromatosis Type I- and also in NPcis mice KO for c-Fos.