PIK3CB and head and neck cancer: Yet, the significant co-expression we found between the ErbBs and both PIK3CB and PIK3C2B, and the demonstrated link between constitutive Akt activation and resistance to EGFR inhibition in head and neck cancers [54,64,65], suggests that PI3K inhibitors could have added therapeutic effects also in PIK3CA non-mutant tumors (Figure 2b).