These results suggested that the ‘loser’ cells are eliminated by mechanical compression. Indeed, when we modified the coculture ratio, we found that ZO-1/ZO-2 double KO cells (magenta) needed to be surrounded by normal cells (green) to be eliminated. (9/n)

ROCK was required to form supracellular actomyosin cables formed in the normal cells at the clone boundary. The actomyosin cables constricted in a purse-string-like manner to eliminate ZO-1/ZO-2 double KO cells. (8/n)

We performed a chemical compound library screening to elucidate the underlying molecular mechanisms and found that ROCK plays a key role in eliminating ZO-1/ZO-2 double KO cells. (7/n)

Importantly, epithelial barrier function measured by transepithelial electric resistance progressively recovered as the elimination proceeded. These results suggested that cell-cell junction-deficient cells are eliminated from epithelia to maintain epithelial barrier homeostasis. (6/n)

Indeed, by carefully observing the time course of the coculture, we found that ZO-1/ZO-2 double KO cells are eliminated by apoptosis when surrounded by normal cells! (5/n)

At first, we thought it was a simple mistake, but finally, we realized that some KO cells remained at the edge of the colonies. This observation reminded us of the cell competition phenomena initially characterized in Drosophila. (4/n)