TP53 and neoplasm: Once Δ40p53 was the major component of p53 cytoplasmic aggregates in EC cells, we propose here that Δ40p53 is a key modulator of p53 tumor suppression and oncogenic activities in EC cells (Fig. 5), as shown in hepatocellular carcinoma, melanoma, and breast tumors (21), in which this isoform presents a dominant-negative role over fl-p53.