(A) Representative immunofluorescence confocal microscopy images of young, aged and aged + CASIN (5µM) treated LT-HSCs for the proximity ligation assay (red signal), testing the extent of close physical interaction of Cdc42 and borg4. A red fluorescent signal indicates close proximity of the two proteins tested. Nuclei were stained with DAPI (blue), scale bar= 5µm. (B) Quantification of the level of fluorescent signal in young, aged and aged + CASIN (5µM) treated LT-HSCs to quantify the Cdc42-borg4 proximity interaction. Data are normalized to the mean fluorescence signal of aged LT-HSCs. 3 biological repeats, n=at least 17 cells per condition, error bars indicate mean±SEM, unpaired t-test, ****P<0.0001. (C) Representative immunofluorescence confocal microscopy images of young, aged and aged + CASIN (5µM) treated LT-HSCs for the proximity ligation assay (red signal), testing the extent of close physical interaction of borg4 and septin 7. A red fluorescent signal indicates close proximity of the two proteins tested. Nuclei were stained with DAPI (blue), scale bar= 5µm. (D) Quantification of the level of fluorescent signal in young, aged and aged + CASIN (5µM) treated LT-HSCs to quantify the borg4-septin 7 proximity interaction. Data are normalized to the mean fluorescence signal of aged LT-HSCs. 3 biological repeats, n=at least 17 cells per condition, error bars indicate mean±SEM, unpaired t-test, ***P<0.001, ****P<0.0001. 