Absence of BRCA2 protein in FA-D1 cells. (A). Kindred 1-sibling 2 does not express BRCA2. Lymphoblast cell lines established from an FA subtype A patient (lane 1), an FA subtype D1 patient (lane 2), a control non-FA patient (lane 3), or member of kindred 1 (lanes 4-6) were lysed and immunoblotted with an antibody against FANCD2 (top panels) or BRCA2 (bottom panels). Cell lysates from sibling 2 contained ubiquitinated FANCD2 but were missing the BRCA2 protein. (B). Kindred 2-sibling 2 does not express the BRCA2 protein. Lymphoblast cell lines established from a control non-FA patient (lanes 1 and 6), an FA subtype A patient (lane 2), an FA subtype D1 patient (lane 5), or kindred 2-sibling 2 (lanes 3, 4, and 7) were lysed and immunoblotted for FANCD2 (top panels, lanes 1-4) or BRCA2 (bottom panels, lanes 5-7). Lanes 3 and 4 represent 2 different lysates from sibling 2. Ubiquitinated FANCD2 was detectable in lysates from sibling 2, but FANCD1/BRCA2 was absent.