Transport proteins that pump solutes into the cell can be regulated by cell turgor pressure. Decrease in turgor pressure causes shrinkage while increase in turgor pressure brings about swelling. When the cell membrane has low turgor pressure, it is flaccid. Pressure probes measure turgor pressure via displacement. This is called "prolonged capillary refill" and "poor skin turgor". Enzymatic activity and turgor pressure act to weaken and extrude the cell wall. Hyphal growth is directly related to turgor pressure, and growth slows as turgor pressure decreases. These cells grow rather quickly due to increases turgor pressure. It effectuates leaf motion due to reversible changes in turgor pressure, which occurs without growth. Some protists do not have cell walls and cannot experience turgor pressure. Hydraulic turgor pressure creates this rigidity, along with the wall structure. This increases the cell's volume and turgor pressure. If water loss leads to a significant decline in turgor pressure, the cell will plasmolyze. The drop in turgor pressure is reversible but slow. Without turgor, plants will lose structure and wilt.