In utero electroporation was performed as previously described33 with minor modifications. Briefly, C57BL/6J mice pregnant at E15 days were anaesthetized with isoflurane (Piramal UK). Needles for injection were pulled from P-97 Flaming/Brownglass capillaries (World Precision Instruments, Sarasota, FL, USA). shRNA solutions were mixed in 10 mM Tris, pH 8.0, Tripan blue and plasmid and injected at a concentration of 0.5–1.5 µg/µl each construct. Five pulses of 38V (50 ms ON, 950 OFF) were applied using 5 mm electrodes and a dedicated electroporator (LIADE National University of Córdoba, Argentina). The embryos were placed back into the abdominal cavity to avoid excessive temperature loss and the abdominal cavity was sutured.