ALK and neuroblastoma: ,8,11 In response to chemotherapy or (anaplastic lymphoma kinase (ALK) inhibitor treatment, this phenotypic plasticity by which cells in the ADRN state facultatively switch to the MES state could play a key role in the ability of neuroblastomas to develop therapy resistance, where the fraction of cells with an adopted MES phenotype quickly expand and constitute the majority of the complete cell population in response to chemotherapy or ALK inhibitor treatment.2