Fig. 3.
The Mos/MAPK/Rsk pathway inhibits binding of the MRN complex to dsDNA. (A) Xenopus crude interphase extracts (S extracts) were treated with control MBP or MBP-Mos and then with SL0101 or DMSO, and double-stranded poly (dA-dT)70. Samples were analyzed for ATM autophosphorylation by immunoblotting. (B) Xenopus crude S extracts were incubated with active RSK for 15 min before the addition of dsDNA. Samples were analyzed for ATM autophosphorylation by immunoblotting. (C) Crude S extracts were pretreated with MBP-Mos or MBP alone and caffeine and were incubated with biotin-tagged dsDNA-bound avidin beads. The amount of ATM bound to beads was analyzed by immunoblotting. DNA bound Ku70 was used as loading control. (D) Xenopus crude S extracts were pretreated with MBP-Mos or MBP ± caffeine or SL0101 and were incubated with biotin-tagged dsDNA which was bound to avidin beads. The amount of Mre11 protein bound to beads was analyzed by immunoblotting. Ku70 was the loading control.