The ability of an in vitro assay to produce reliable biomedically relevant information is essential in drug development; therefore, it is necessary that the cells used in this testing mimic the phenotype of cells within the target tissue [7,8]. 2D cell culture (i.e. monolayer culture) is conventionally used in in vitro drug candidate testing; however, limitations of 2D culture suggest that an alternative method should be considered. These limitations include the lack of cell–cell and cell–extracellular matrix (ECM) signalling thatoccurs in the 3D (three-dimensional, multi-cellular spheroids) in vivo environment where such signals are essential to cell differ- entiation, proliferation and a range of cellular functions [9,10]. For example, integrins, which are cell surface receptors, anchor cells to the ECM and are also involved in the cells’ interpretation of biochemical cues from their local environment [11,12]. It is prob- able, therefore, that 3D cellular assays would be more analogous to – and so predictive of – in vivo events compared to more simplified 2D cultures in which essential signalling pathways may have been lost or, at least, compromised [13]. The use of 3D in vitro systems in drug research and development has, therefore, been suggested as a potential link to bridge the gap between monolayer cultures and animal model studies