ASCL1 and neuroblastoma: However, it seems likely that the absolute level of ASCL1 protein is critical to determine whether it supports proliferation or differentiation in a particular neuroblastoma cell line; siRNA knockdown led to a reduction of ASCL1 in Kelly cells, yet these cells have an endogenous level of ASCL1 that is considerably higher than IMR32 or SH-SY5Y cells, so significant ASCL1 protein remained even after knock-down (Wang et al., 2019).