CHEK2 and breast cancer: To determine the functional effect of CHEK2 1100delC truncation, we established LCLs from three female CHEK2 1100delC carriers, 00.003.2053 (unaffected at age 54), 00.003.2070 (unaffected at age 79 and no family history of breast cancer except in her daughter and granddaughter) and 00.005.0442 (breast cancer at age 52), as well as LCLs from healthy wild-type individuals (98.004.0039) as controls.