Rajagopal et al. investigated the CSF proteome from 33 children with MB compared to 25 age-matched controls using 2D- gel electrophoresis and found that levels of prostaglandin D2 synthase (PGD2S) was six-fold lower in the CSF of tumor samples suggesting a host response to the presence of the tumor [120,121]. Here, PTGDS is linked to neoplasm.