CELF1 and breast cancer: Additional analysis revealed comparatively low proportions of tumour cells staining for CELF protein in smaller early stage tumours without detectable nodal involvement (T1N0 mean 50.2, s.d. 40.3), with progressively increasing rates of positivity in larger tumours that had spread to the lymph nodes (T2N>0 mean 68.3, s.d. 33.8; T3N>0 mean 81.5, s.d. 24.8; two-sided P=0.0352, Jonckheere–Terpstra trend test; Fig. 7h), cumulatively indicating that increased CELF1 protein expression is associated with the progression and metastatic spread of breast cancer.