In order to elucidate if the effects of Δ40p53 knockdown were specific to tumour cells, acini formation assays were performed in normal human mammary epithelial cells MCF-10A in which Δ40p53 or p53 were stably knocked down (MCF-10A-shΔ40p53 and MCF-10A-shp53, respectively; Fig. 4A, B). Here, TP53 is linked to neoplasm.