In addition, two knock-in conditional Trp53R172H (corresponding to human TP53R175H) and Trp53R270H (corresponding to human TP53R273H) alleles (referred to as Trp53LSL-mut), in which a loxP flanked STOP cassette was inserted into the first intron to block mutant Trp53 expression, have been utilized to study different types of cancers including breast cancer7–9. The gene discussed is TP53; the disease is cancer.