Whole transcriptome analysis of the ERα synthetic fragment P295-T311 (ERα17p) identifies specific ERα-isoform (ERα, ERα36)-dependent and -independent actions in breast cancer cells

► A peptide issued from the ERα P295LMIKRSKKNSLALSLT311 structure (ERα17p) is investigated. ► ERα17p internalizes in breast cancer cells, independently of the presence of ERα. ► ERα17p induces a massive early transcription in breast cancer cell lines. ► ∼75% of transcripts are common with E2. Non-E2-related actions include apoptosis and migration. ► ERα and ERα36 estrogenic transcriptional effects are opposite.