PLK4 mRNA and protein are commonly found upregulated in gastric cancer; induced overexpression of PLK4 in gastric cancer cells leads to centrosome amplification and chromosomal instability and suppresses primary cilia formation; higher PLK4 expression positively correlates with an advanced stage and, in multivariate analysis, with a shorter disease-free survival (DFS). The gene discussed is PLK4; the disease is gastric cancer.