NR3C1 and breast carcinoma: To uncover novel interacting partners of GR at the chromatin level, we performed quantitative label-free mass spectrometry (MS), chromatin immunoprecipitation–selective isolation of chromatin-associated proteins (ChIP-SICAP) (25), using mouse mammary carcinoma cells treated or untreated with dexamethasone, a steroid hormone known to rapidly translocate the steroid receptor GR to the nucleus and promote its binding to chromatin and gene regulatory functions (fig.