Sensitive mouse strains (e.g., C3H or the hybrid strain B6C3F1) develop Ctnnb1-mutated neoplasms within 12 mo of PB exposure with high incidence, whereas tumor-resistant strains (e.g., C57BL/6) only develop liver tumors after an initiating mutagenic event and long-term PB exposure (Table S1 and references within). The gene discussed is CTNNB1; the disease is neoplasm.