TP53 and neoplasm: Assessment of Lyn expression by qRT-PCR using a probe targeting exon 4 demonstrated that there was a significant reduction in Lyn expression in BlgCre Brca1fl/fl p53+/− Lynfl/fl tumour cells compared to that in wild-type cells, but again, in some individual tumours, Lyn exon 4 expression was comparable to that seen in Lynwt/wt tumours (Fig. 3G).