Table 2.

Rules for the emergence and activation of cell membrane receptors in the IBCell model and their link to model equations. Cell membrane receptors are colour coded as in Fig. 2A

Cell receptors	Receptor activation/emergence	Model equations
Adhesion (green)	Activated when two receptors from distinct cells are close enough	Adhesive forces F(l, t) in (3) and (4)
ECM (yellow)	Activated when the expression of ECM proteins exceeds the threshold	ECM γ (X(l, t)) kinetics in (7)
Growth (blue)	All receptors free from any cell–cell or cell–ECM contacts (a default state)	Sources S+(Yk, t) inside and sinks S−(Zm, t) outside the growing cell, (5)
Death (grey)	Emerge after detachment from a polarized or from another dying cell	Sinks S− (Zm, t) inside and sources S+(Yk, t) outside the dying cell, (5)
Apical (cyan)	Emerge during the development of a cell’s apical membrane domain	Adhesive forces F(l, t) in (3) and (4) are disassembled; all extrinsic signals are blocked