GEOapplication/xmlftp://ftp.ncbi.nlm.nih.gov/geo/series/GSE19nnn/GSE19639/primaryOK2000000GenomicsHomo sapiensExpression profiling by arrayhttps://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE19639GEOGSE0falseHyperactivation of PI3K promotes escape from hormone dependence in estrogen receptor-positive breast cancerHyperactivation of phosphatidylinositol-3 kinase (PI3K) promotes escape from hormone dependence in estrogen receptor-positive breast cancer. A significant fraction of breast cancers exhibit de novo or acquired resistance to estrogen deprivation. We used gene expression microarrays to identify genes and pathways that are commonly dysregulated in ER+ cell lines with acquired hormone-independent growth. MCF-7, ZR75-1, MDA-361, and HCC-1428 ER+, estrogen-responsive breast cancer cells were cultured under hormone-depleted conditions (10% DCC-FBS) for several months until sustainable hormone-independent cell populations emerged.2010/06/15GSE19639GSM490061GSM490050GSM490060GSM490063GSM490052GSM490051GSM490062GSM490043GSM490054GSM490065GSM490053GSM490064GSM490056GSM490045GSM490066GSM490055GSM490044GSM490058GSM490047GSM490046GSM490057GSM490049GSM490048GSM49005957019639Homo sapiens[21346144][20530877]