STAT1 phosphorylation at tyrosine 701 is reduced in MEFs and B lymphoblasts.

(A) Immunoblot analysis demonstrates that phosphorylation of STAT1 is reduced in both nuclear extracts and total cell extracts (upper and middle panel respectively) from FancC^−/− MEFs (MEF61) (lanes 5 through 8) compared with WT cells (MEF11.1) (lanes 1 though 4) following stimulation with 1 ng/mL IFNγ for the indicated times. Total STAT1 levels (lower panel) were equivalent (lanes 1 through 4 compared with lanes 5 through 8). (B) Phosphorylation of STAT1 (upper panel) is reduced in total cell extracts from HSC536N (lanes 3 and 4) and HSC536N/neo (lanes 7 and 8) compared with JY (lanes 1 and 2) and HSC536N/FANCC (lanes 5 and 6) following stimulation with 1 ng/mL IFNγ at 37°C for 15 minutes (lanes 2, 4, 6, and 8). Total STAT1 levels were slightly higher in the mutant cells (but phosphorylation levels are reduced) (lower panel).