Cells may adhere to one another by cadherin molecules on the cell surface. Cadherin interactions allow cells to form aggregates. The formation of cell aggregates via adhesive biomolecules can be modeled by a reorientation operator with transition probabilities defined as P ( s → → s O | s N ) = 1 Z exp ⁡ ⁡ [ β β G ( s N ) ⋅ ⋅ J ( s O ) ]