CHRNA9 and cancer: To experimentally validate our SIM strategy in general, we examined 18 representative interacting partners of CHRNA9 (Supplementary Fig. 27a, b; details in Supplementary Note 10) via immunoprecipitation (IP; Supplementary Fig. 30) or Förster resonance energy transfer (FRET; Fig. 6a and Supplementary Fig. 31) assays42 in human cancer cells.