TP53 and cancer: It has also been shown that p53 mutations may alter p53 isoform levels: most TP53 alternative splicing events associate with p53 frame-shift mutations (68) and transfection of common mis-sense mutant p53 increased the level of Δ160p53 (see below) (69), although this still represented only 10% of total p53 in transfected cells and much less in cancer cells that endogenously express the same mutation.