CHL1 and melanoma: To analyze and compare the tumour progression between two models of melanoma (WT vs. TPC2 KO) and elucidate the role and the impact of the two-pore channel 2 (TPC2) gene in tumour growth on melanoma cells in vivo, we subcutaneously injected B16 and CHL-1 WT or TPC2 KO cells into mice.