Fig. 2. The APC armadillo repeat domain localizes to cortical APC clusters. Basal sections of cells expressing different APC domains (shown schematically on left) fused to GFP (GFP: green) co-stained for endogenous full-length APC (APC: red) or for ß-tubulin (Tub: red). Note that the APC antiserum (anti-APC) does not recognize the deleted GFP-APC fusion proteins because they lack the epitope. (a-c) Full-length GFP-APC co-aligns along MTs (white arrowheads in a-c) and accumulates in cortical clusters at the tip of cell extensions distal to the MT ends (black arrowheads in a-c). (d-f) GFP-APCwoE1 co-aligns with MTs but does not colocalize with endogenous APC in clusters at the tip of cell extensions (black arrowheads in d-f). (g-n) GFP-APCE1X1 localizes to the cortical APC clusters (black arrowheads in g-i), but does not co-align with MTs (black arrowheads in k-n). (o-q) APCARM-GFP does not co-align with MTs but colocalizes with endogenous APC in the cortical clusters (black arrowheads in o-q). (r-t) APCARM-Rep.-GFP shows weak colocalization in some APC clusters (black arrowheads in r-t) but not others (white arrowheads in r-t).