CXCR7 is required for the interaction between oestrogen receptor and PELP1. wt-MCF7 and MCF7-LTED cells were transfected with sicontrol or siCXCR7. (A) Oestrogen receptor/oestrogen response element (ER/ERE) transactivation was monitored with an ERE-linked luciferase reporter and pCH110 (β-galactosidase control) and expressed relative to dextran-coated charcoal (DCC) control. (B) Expression of TFF1 was assessed by quantitative RT-PCR, as previously described. Error bars represent × SEM. *P <0.05, **P <0.01. (C) Immunoblot analysis of kinases associated with phosphorylation of ER in response to CXCR7 depletion. (D) MCF7-LTED cells were left untreated or transfected with sicontrol, siCXCR7, siPELP1 or siESR1, immunoprecipitated for PELP1; and immunoblotted for ER or vice versa. The data shown are representative of three independent experiments. CXCR, Chemokine C-X-C receptor; E2, Oestradiol; IP, Immunoprecipitation; JNK, c-Jun N-terminal kinase; LTED, Long-term oestrogen deprivation; PELP, Proline-, glutamic acid- and leucine-rich protein 1; si, Small interfering; wt, Wild type.