The first described CK1 inhibitors CKI-7 (IC50 = 6 μM for CK1δ) [48] or IC261 (IC50 = 1.0 μM for CK1 δ/ε, IC50 = 16 μM for CK1α) [49] were not very specific but showed activity against pancreatic tumors in a xenograft mouse model [50] as well as in a MYC-driven neuroblastoma model [51]. This evidence concerns the gene CSNK1A1 and neuroblastoma.