Anti cxcr7 antibody

Sections were dewaxed and rehydrated as described above. After rinsing with distilled water and phosphate-buffered saline (PBS), sections were incubated with 25% goat serum in TBS containing 5% (w/v) bovine serum albumin (BSA) for 30 min at RT. Subsequently, primary antibodies against CXCR7 (rabbit polyclonal anti-CXCR7, Abcam, dilution of 1∶400, Cambridge, UK), CXCR4 (rat monoclonal anti-CXCR4, R&D System, dilution of 1∶20, Wiesbaden, Germany), LIN28a (rabbit polyclonal anti-LIN28a, A177 Cell Signaling, dilution of 1∶50, Darmstadt, Germany) and SALL4 (mouse monoclonal anti-SALL4, Abcam, dilution of 1∶150, Cambridge, UK) were applied and sections were incubated in a humid chamber at 4°C for 60 min. The specificity of the anti-CXCR7 antibody was confirmed immunohistochemically using peptide competition (Fig. S2A–D). For this, the human GPCR RDC1 peptide was applied in a ratio of 1∶1 with the anti-CXCR7 antibody to testicular tissue sections (14 dpp, incubation 1 hr at RT, Abcam, Cambridge, UK). Incubation with corresponding immunoglobulin G (IgG) fractions was used as negative control. Following two PBS washing steps the appropriate Alexa fluor 488-linked or 546-linked secondary antibodies, diluted in TBS/5% BSA, were applied for 45 min at RT in the dark. Cells were counter-stained with Hoechst for visualization of nuclei (33258, Sigma-Aldrich, Steinheim, Germany).