Fig. S5.

Depletion of MHF1, MHF2, or MHF1 and -2 induces replication stress at the ALT telomeres. U2-OS cells were transfected with siRNA targeting Luciferase (Luc), MHF1, MHF2, or MHF1 and -2. Cells were then costained with an antibody recognizing Chk1-pS345 (labeled as pChk1, A–C) or BLM (D–F), together with a PNA probe recognizing the G-rich strand of telomeres (TelC) or an antibody recognizing TRF1. All nuclei were stained with DAPI. More than 200 cells were counted for each sample. All error bars are SD obtained from three different experiments. Standard two-sided t test: ***P < 0.001.