The breast cancer sample tissue microarrays (BC08118) for IHC analysis were purchased from Biomax (Rockville, MD, USA). The same tissue samples were stained with RBM38 and ZO-1 antibody respectively. The RBM38 antibody (LifeSpan Biosciences, Seattle, WA, USA) was used at the dilution of 1 : 300. The ZO-1 antibody (Abcam, Cambridge, MA, USA) was used with a concentration of 10 μg ml−1. The IHC staining was conducted and analysed as previously described (Shi et al, 2015 (link)).