CTC1 and brain neoplasm: Thus, key factors contributing to different steps in the assembly and function of the pre-replicative complex are increased in expression in ALT brain tumors, including the small RPA subunit, RPA3, which, intriguingly, has been also described as part of the Ctc1-Stn1-Ten1 complex, which binds to single-stranded DNA and protects telomeres, independently of the shelterin complex [40].