The forward primer described in the manuscript corresponding to the 5' junction of the 3’ homology arm is imprecise. Please find below the exact position of the junctions of both homology arms 5’ and 3’. The genomic sequence in between the homology arms was deleted in DroncKO. TTGGCGCGCCCAATAAGCGGAGTCA……deleted sequence……TGATGAATACTACTTTGGTACATG The correct Forward primer containing the BglII restriction site of the 3’ homology arm is: attgccaAGATCTTGATGAATACTACTTTGG