RB1 mutation in HPG-RBT-12L cells, as well as in the parental tumor was identified as a point mutation in exon 15 (NM_000321.2(RB1):c.1421G>T) associated with altered splicing, while for the HPG-RBT-26 cells and tumor in exon 23 (NM_000321.2(RB1):c.2359C>T(p.Arg787*)), it was associated with a premature stop codon. This evidence concerns the gene RB1 and neoplasm.