PTPN6 and systemic lupus erythematosus: In this highly connected PPI cluster, 5 proteins (two SLE disease proteins: protein tyrosine phosphatase, non-receptor type 6 [PTPN6] and LYN proto-oncogene, Src family tyrosine kinase [LYN]; and three essential targets: STAT1, Janus kinase 2 [JAK2] and FYN proto-oncogene, Src family tyrosine kinase [FYN]) appeared to act as hub proteins based on their high degrees of association.