PIK3CD and squamous cell carcinoma: In addition, inhibitors to pathways that involve phosphoinositide 3-kinase (PI3K), survivin, Janus kinase (JAK), matrix metallopeptidase 9 (MMP-9), vascular endothelial growth factor (VEGF), and mitogen-activated protein kinases (MAPKs) are also under investigation to determine their treatment efficacy in squamous cell carcinoma [14,18,19].