ERBB2 and cancer: Although KRT19 regulates EGR1/PTEN/AKT, β-catenin/NUMB/NOTCH, and HER2/ERK/SP1 cascades [29,46,47], we focused on the AKT, GSK3β, ERK, Src, and JNK signaling pathway in this study, as these signaling pathways are crucially involved in cancer progression [52,53,54,55,56].