Some proteins are expressed periodically during a specific stage of the cell cycle or as a response to various stimuli. As a result, at any given time some cells express the protein of interest and some do not. In the Cell Atlas we denote these images as single-cell variation (SCV). An example of a protein with such variations is CCNB1.

CCNB1, shown here in U-251 MG cells, is essential for cellular proliferation. The abundance of CCNB1 oscillates across the cell cycle, and peaks during G2/M phase. CCNB1 is expressed in the cytoplasm during interphase and translocate to the nucleus during G2/M transition. Overexpression of CCNB1 can lead to uncontrolled cell proliferation, which is one of the Hallmarks of cancer. CCNB1 expression level is used for the prognosis of cancer patients.

We, in the Cell Atlas project are putting a big effort into characterizing and understanding these protein variations to explain mechanisms underlying diseases.

-Diana Mahdessian