In a pioneering study by Bernstein and Bamburg, it was observed that the actin-binding protein "actin depolymerisation factor (ADF)/cofilin", a factor that promotes actin filament depolymerisation, competed with tropomyosin for binding to the actin filament. The expression of Tropomyosin 5NM1 in neuronal cells eliminated ADF/cofilin from the growth cone region, leading to more stable actin filaments. However, the increased expression of Tropomyosin Br3 was observed to recruit ADF/cofilin to actin filaments bound to the Tropomyosin Br3 isoform within the lamellipodium, which led to the disassembly of actin filaments. This phenomenon, whereby a specific tropomyosin isoform directs specific interactions between actin-binding proteins, and the actin filament has been observed in a variety of model systems with a range of different binding proteins (reviewed in Gunning et al., 2008). These interactions, under the influence of tropomyosin isoforms, allow actin filaments to be involved in a diverse range of cellular functions.