To better understand the mechanisms underlying the association of NUSAP1 overexpression and cancer aggressiveness, we used AP–MS to identify novel interactions between NUSAP1 and several proteins with described functions in R-loop biology and DDR, including DHX9 [41,53], ILF2 [40,43,54], HNRPC [55,56], FUS [57,58,59], and RBMX [60,61]. This evidence concerns the gene FUS and cancer.