Phosphoproteome of MCF7 breast cancer cells treated with estradiol and BI2536

Triple SILAC phosphoproteome experiment of hormone deprived MCF7 cells treated with estradiol (E2) in presence or absence of the PLK1 inhibitor BI2536. Conditions were as follows: light (L) population: 1h DMSO, 30min EtOH; medium (M) population: 1h DMSO, 30min E2; heavy (H) population: 1h BI2536, 30min E2. Biological replicates: A and B. Phosphopeptides were enriched from soluble and insoluble fraction using a two step enrichment protocol consiting of strong cation exchange and TiO2 affinity chromatography. The peptides were analyzed on an Orbitrap Velos mass spectrometer linked to an online nanoflow HPLC system via a nanoelectrospray ion source and fragmented via higher-energy C-trap dissociation (HCD). Analysis was carried out using MaxQuant (v. 1.2.2.5) with standard settings including STY phosphporylation as variable modification.