Definitely smoking. That’s the prime cause of lung cancer.
Answer:
At the microscopic level of a visceral muscle cell are actin and myosin filaments. They slide past each other in an antiparallel manner to shorten the distances between their ends. In a smooth muscle cell, the ends of chains of these functional units are attached to the cell membrane. They are several in a cell arranged in an elaborate framework. They contract together and deferentially to enable the muscle to contract as needed.
A.) ethical is a concern raised
Answer:
If they didn't differentiate then the stem cells would stay the same type and if it somehow kept multiplying then they would just be a massive blob with no actual form or way of functioning.
The fact that gravity exists as it can be repeatedly tested and verified