PIK3CA and neoplasm: We are the first group, to our knowledge, to report that ectopic expression of ErbB2/ErbB3 mutants in GBC cells upregulated PD-L1 expression, which suppressed T cell-mediated cytotoxicity and drove tumor growth and metastasis.228 Mechanistically, ErbB2/ErbB3-mediated expression of PD-L1 was dependent on activation of the PI3K/Akt signaling pathway.