NR3C1 and cancer: Similar results were observed in tumorsphere assays in which TNBC cells were plated at limiting dilution in ultra-low attachment dishes as an in vitro readout of cancer stem-like cell behavior [47]; while addition of Dex to sphere media was without effect, MDA-MB-231 cells harboring S134A mutant GR failed to form tumorspheres relative to cells expressing endogenous wt-GR (Fig. 3f).