NTRK1 and medulloblastoma: In attempting to examine the possible mechanisms underlying the TrkA-mediated induction of cell death, Li et al. (2010) made the intriguing observation that a specific inhibitor of casein kinase 1 (CK1) was able to block both the induction of macropinocytosis and the associated death of the medulloblastoma cells caused by activation of TrkA.