CLDN1 and neoplasm: This was further supported by separation of RMC cells into a ‘stressed’ epithelial-like phenotype with higher levels of cytokines (IL8, LCN2), keratins and epithelial markers such as CDH1, CLDN1 and into RMC2 cells with higher expression of mesenchymal markers such as SFRP2, CDH2 and FN1. Thus, this RMC tumour comprised epithelial-like RMC1 cells and mesenchymal-like RMC2 cells (Fig. 1j).