TP53 and neoplasm: We subsequently found that both the parental and lung metastatic lesion-derived mutant p53 G245D UM-SCC-1 cell lines exhibited a much more aggressive growth phenotype in in vitro three-dimensional (3D) collagen culture than did the control cells; the aggressive phenotype was characterized by the formation of tumor spheroids with numerous protrusions invading into the surrounding collagen matrix (Fig. 1a), supporting the GOF activities of G245D mutant p53 in these cells.