B/C NOTCH1 ICD outcompetes L3MBTL3 for binding to RBPJ in a dose-dependent manner. IPs were performed in CRISPR/Cas9-mediated L3MBTL3 knockout (KO) HEK293T cells. (B) SBP-FLAG-RBPJ and HA-L3MBTL3-Δ(SAM) in the presence of an increasing amount of HA-NOTCH1 ICD. The L3MBTL3-Δ(SAM) mutant construct was used instead of the L3MBTL3 WT construct in order to allow the analysis of both NOTCH1 ICD and L3MBTL3 proteins in the same Western blot. CRISPR/Cas9 sg-L3MBTL3-resistant plasmids were used to express HA-L3MBTL3-Δ(SAM). The experiment was independently replicated thrice. WB: Western blot; IP: immuno-precipitation. 