A patient with ALL/t(17; 19) (Key resources table) who initially presented with dexamethasone-sensitive leukemia but later relapsed with steroid-resistant disease (due to a homozygous deletion of the glucocorticoid receptor NR3C1) was used as a model to study the effects of dexamethasone in our i-niche system. Here, NR3C1 is linked to leukemia.