What makes some cells become “leaders” and others “followers”?

BACKGROUND INFORMATION
Follow the leader? This image shows cells in a primary breast cancer tumor invading the surrounding muscle tissue (blue). Both the green- and pink-stained cells are tumor cells, but the pink cells represent “leader” cells: cells that break off from the main body of the green tumor and begin to metastasize, a process by which cancers from a primary tumor invade and colonize other tissues. These leader cells are both genetically and behaviorally different from the main body of the tumor. Researchers hope to identify the genetic mutations that cause cells to become leaders to give them new opportunities for treating breast cancers and preventing metastasis.
What makes some cells become “leaders” and others “followers”? Can we predict if a cell will become a “leader” or “follower”?
Investigate mutations in specific genes that can lead to abnormal cell division and proliferation, which can lead to cancer. Provide detailed information, in your own words, with references provided, about the specific mutation you have chosen and its role in the progression of cancer. Please submit 500-750 words, using American Psychological Association (APA) 6th edition format.
This resource has been adapted from Howard Hughes Medical Institute.