ACAP4, a GTPase-activating protein (GAP) for the ADP-ribosylation factor 6 (ARF6), plays import roles in cell migration, cell polarity, vesicle trafficking and tumorigenesis. Similarly, the ubiquitously expressed adaptor protein CrkII functions in a wide range of cellular activities, including cell proliferation, T cell adhesion and activation, tumorigenesis, and bacterial pathogenesis. Here, we demonstrate that ACAP4 physically interacts with CrkII. Biochemical experiments revealed that ACAP4(550-660) and the SH3N domain of CrkII are responsible for the interaction. Functional characterization showed that the interaction is required for the recruitment of ACAP4 to the plasma membrane where ACAP4 functions to regulate the recycling of the signal transducer integrin beta 1. Thus, we suggest that the CrkII-ACAP4 complex may be involved in regulation of cell adhesion. (C) 2019 Elsevier Inc. All rights reserved.