IIICF/c is an ALT cell line [51] derived from IIICF Li-Fraumeni Syndrome fibroblasts containing one mutant (essentially null) and one wild-type (wt) TP53 allele [52], that became immortalized spontaneously via a series of genetic changes that included loss of the wt TP53 allele [51]. This evidence concerns the gene TP53 and Li-Fraumeni syndrome.