NR3C1 and acute lymphoblastic leukemia: In glucocorticoid-sensitive ALL cells, treatment with glucocorticoids activates the GR, which up-regulates KLF13 expression, which is abrogated in glucocorticoid-resistant ALL.20 The GCS-3/dexamethasone combination significantly increased KLF13 expression compared to either single agent at 24 h (Fig. 5a, c).