However, although overall median proportion scores in breast tumour tissue were already 80%, the proportion of tumour cells positive for CELF1 expression significantly increased as a function of tumour grade (Grade I mean 60.1, s.d. 32.9; Grade II mean 67.2, s.d. 34.5; Grade II–III mean 82.9, s.d. 23.6), revealing an inverse relationship between CELF1 expression level and differentiation state (one-sided P=0.0464, Jonckheere–Terpstra trend test; Fig. 7g). This evidence concerns the gene CELF1 and breast neoplasm.