PIK3CA and pachyonychia congenita: The oncogenic erythroblastic leukemia viral oncogene homolog (ErbB), focal adhesion, mitogen-activated protein kinase, phosphoinositide 3-kinase (PI3K)-Akt, and Ras signaling pathways are the key pathways responsible for the various mechanisms involved in the pathological processes of PC cells and tumors, and they have important roles as efficacious targets and biomarkers for survival and therapeutic response rate in patients with PC [145–151].