MAS1 (a tyrosine kinase protooncogene) was reported to show monoallelic expression (parent-of-origin
not determined) in 4 human breast samples (3 malignant, 1 benign) by nested RT-PCR (Miller
N et al, 1997), but others have shown no evidence of imprinting in humans or mice (Riesewijk
AM et al, 1996; Schweifer
N et al, 1997).