Why are we not falling apart?
We are but a collection of cells, but why we are not falling apart? One of the reasons for that is that the stickiness protein E-cadherin is delivered from the cell interior to the cell boundary, where, when absorbed into the boundary, it is attaching to its twin in the neighboring cell. Because cells are small-scale highly diffusive environments, the mechanism of delivery of the protein to its biologically relevant location is an active process of molecular walkers dragging the vesicle with the protein along "railroads" (microtubule cytoskeleton) to the cell boundaries. In this talk I will present a sequence of toy models en route of understanding some aspects of this intracellular transport, which leads to creation of coherent tissues. The two problems considered in this talk are - what drives the self organization of the cytoskeleton (the " railroad" network for the protein delivery), and a rule of thumb of how to determine from the protein density data in the cell which type of molecular motor is responsible for its delivery.