While Fahraeus (Δ40p53), Harris (Δ133p53), Lane and Bourdon (all p53 isoforms), as well as several reports by others evaluating expression in different tumor types (reviewed in [16]) have provided some initial insights about p53 alternative splicing and biological effects, the role and control of p53 isoforms in normal and in tumor biology remain poorly understood. This evidence concerns the gene TP53 and neoplasm.