ATOH1 and neoplasm: Tumor‐initiating ability is a property of CSCs.[14] Serial tumor xenograft dilutions significantly lowered the tumor initiation capacity from 1 in 603611 AGS cells (control) to 1 in 3488397 cells (ATOH1 overexpression) (P = 0.008; Figure 2F; Figure S10A–E, Supporting Information).