MAST1 was N-terminally EGFP-tagged and overexpressed in HEK293 cells. Two constructs of MAST1, (WT and S90A S161A), as well as an EGFP only control, were compared in a pairwise manner to identify specific interactors of MAST1. EGFP-MAST1 was affinity-purified using the GFP-Trap system and then incubated with the lysate of dorsal brain organoids. The interacting proteins were analyzed by mass spectrometry.