Identification of HSPC111 as an estrogen-regulated target of c-Myc. Cells were pretreated with ICI 182780 for 48 hours. Parental MCF-7 cells were then treated with either 17β-estradiol (diamonds) or vehicle (squares), and MCF-7/MycWT (triangles) and empty vector (squares) cells were treated with zinc. (a) HSPC111 mRNA expression in two probe sets from HG-U133 Plus V2.0 microarray platforms, 6 hours after treatment with estradiol (E2) or vehicle, or after expression of c-Myc (MycWT) or zinc treatment of empty vector cells (empty). (b) RNA was isolated at various time points as indicated and analyzed in triplicate by reverse transcription PCR with HSPC111-specific primers. Expression of HSPC111 is presented normalized to RPLP0. (c) immunoblot analysis of endogenous HSPC111 expression in whole cell lysates at time points up to 24 hours. Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) was used as a loading control. Representative blots and densitometric analyses from three independent experiments are shown.