P2RX7 and neoplasm: However, the interaction between LL-37 and the tumor can also be indirect, given the expression of its known receptors such as FPRL-1, P2x7, epidermal growth factor receptor (EGFR), and GAPDH on both tumor cells and various types of immune cells [23,24,25,26], implicating the immunomodulatory roles of LL-37 via a direct interaction with immune cells.