In melanoma, PD-L2 expression is also significantly increased in tumor cells with high phosphorylated β-catenin(pS1-βcat protein) expression downstream of the WNT/β-catenin signaling pathway (42), and the strong correlation between the high expression of this downstream protein and PD-L2 may offer insights for future tumor treatments targeting the signaling pathway. The gene discussed is PDCD1LG2; the disease is melanoma.