Answer:
After cell
Step-by-step explanation:
In this excerpt, a pause should be made after the word cell. We also have a punctuation mark, an em dash, pointing to that. The em dash can take place of commas, parentheses, colons, and even semi-colons (like in this case), and it indicates the presence of a pause. It's a very versatile mark indicating good writing skills, but its use should be limited to two times in a sentence so that confusion doesn't arise.