We sequenced the Grb10 exons in all our tumor cell lines, which revealed no mutations in the remaining paternal Grb10 allele (sequence data from representative cell lines 881, 963 and 989 are archived at http://www.ebi.ac.uk/ena/browse) and is consistent with preferential loss of the maternal Grb10 allele resulting in functional nullizygosity (Fig 2D). Here, GRB10 is linked to neoplasm.