Characterization of the FA cellular phenotype in transduced hematopoietic cells. (A) G₂/M arrest of transduced LCLs after treatment with melphalan. The human FANCC^−/− lymphoblast cell line HSC536-FAC was transduced with the indicated retroviral vectors. The transduced cells were then treated with melphalan as described in “Methods analysis of G2/M arrest and FANCD2 monoubiquitination in human LCLs.” The proportion of eGFP⁺ cells in G₂/M after melphalan treatment is indicated. NTX indicates nontreated. ▩ represents G₀/G₁; ▨, S; and ■, G₂/M. (B) FANCD2 mono-ubiquitination in transduced LCLs after treatment with hydroxyurea. HSC526-FAC cells were transduced with the indicated retroviral vectors and were then either subject to treatment with hydroxyurea (HU) before cell lysis (+) or were directly lysed without treatment (−). Immunoblot was then performed to visualize the relative abundance of long-form mono-ubiquitinated FANCD2 (L) and short-form nonubiquitinated FANCD2 (S).