PIK3CA and Epstein-Barr virus infection: Western blot analyses revealed that EBV infection led to KDM5B upregulation and concurrently PLK2 downregulation in S26 and AGS cells, alongside with the PI3K/AKT/mTOR pathway activation reflected by the increased levels of p110α (a catalytic subunit of PI3K), p-AKT (Ser 473), and p-mTOR (Ser 2448) (Fig. 7a and Supplementary Fig. 9a).