What is the major factor that influences the direction of expansion of plant cells and ultimately the shape of the cell?

THE AMOUNT OF LIGNIN PRESENT in a cell is responsible for this. Once a plant cell stops enlarging, the primary cell wall is reinforced by a secondary cell wall. The secondary cell wall is made up majorly of lignin, which serves a structural function in plants. It provides a skeletal function and ultimately determined the shape of the cell.

Pro insulin undergoes extensive posttranslational modification along the production pathway .