HAK-actin™ is a pan-species Expansion Microscopy (ExM) compatible probe for actin visualization using U-ExM based protocols. HAK-actin™ binds specifically to F-actin. Its design allows HAK-actin™ to be anchored into the gel and expand faithfully to the original actin structure after the swelling step. HAK-actin™ contains an HA tag epitope, it can therefore be detected post expansion using a pair of anti-HA and species specific secondary antibodies. It combines simplicity through a single protocol and versatility as the fluorophore label on the secondary antibody can be chosen freely. Finally, the primary + secondary antibody boosts fluorescent signal amplification, circumventing volumetric dilution of the fluorescent signal due to expansion. Contains 1 tube of HAK-actin™ for 100 gels.