How cells utilize intracellular spatial features to optimize their
signaling characteristics is still not clearly understood. The physical
distance between the cell-surface receptor and the gene expression
machinery, fast reactions, and slow protein diffusion coefficients
are some of the properties that contribute to their intricacy. This
article reviews computational frameworks that can help biologists
to elucidate the implications of space in signaling pathways. We
argue that intracellular macromolecular crowding is an important
modeling issue, and describe how recent simulation methods can reproduce
this phenomenon in either implicit, semi-explicit or fully explicit
representation.