* Homeostasis is the ability of a cell (or an organism) to maintain a stable internal environment despite external changes.

Let's look at some common ways cells achieve homeostasis:

* Transport: Cells use various mechanisms like diffusion, osmosis, active transport, and endocytosis/exocytosis to move substances across their membranes, regulating the concentration of important molecules.

* Metabolic Reactions: Cells constantly perform chemical reactions (metabolism) to create energy, synthesize essential molecules, and break down waste products. This ensures the right balance of energy and resources.

* Feedback Loops: Cells use feedback mechanisms (positive and negative) to adjust processes based on changes in the internal environment. This allows for fine-tuning and self-regulation.

Now, let's think about what is *NOT* a way cells maintain homeostasis:

* Cellular Specialization: While cellular specialization is crucial for the function of multicellular organisms, it's not a direct mechanism of homeostasis at the cellular level. Specialization refers to cells developing specific structures and functions within a tissue or organ, which contributes to the organism's overall homeostasis.

Therefore, the answer is: Cellular Specialization