Based on the initial observation that endosialidase treatment reduces neuroblastoma cell growth, these cells were used to demonstrate that loss of polySia initiates NCAM trans-interactions, leading to reduced proliferation in favor of more robust survival and neuron-like differentiation due to a sustained activation of the ERK signaling pathway (Seidenfaden et al., 2003; Seidenfaden et al., 2006). The gene discussed is NCAM1; the disease is neuroblastoma.