TP53 and neoplasm: Since elevated levels of Δ133p53 and Δ160p53 relative to FLp53 attenuate its transcriptional activity (Figure 8B, left), and overexpression of FLp53 relative to the isoforms allows regaining it (Figure 8B, right), the tumor-suppressive efficacy of p53 must depend on the balanced expression of FLp53 and its isoforms, highlighting the importance of their relative abundance in cancer cells.