Fig. 4

a Schematic illustration of synthesis process of cationic liposome/protamine complex (LPC) and immunotherapy in Lewis lung cell. b Transmission electron micrograph of LPC/mRNA. Scale bar = 200 nm. c Tumor growth of mice bearing LLC during treatment. Stimulation of CD4⁺T cells (d) and CD8⁺T cells e in the spleen. Data are presented as the mean ± SD (n = 4). *p < 0.05, ***p < 0.001. f and g Spleen cells from mice after administration of different formulations collected 1 week after the final immunization and cultured with CK19 for 72 h. The supernatants were collected and the production of cytokines IL-4 and IL-2 was measured. The results are presented as the mean ± SD of experiments performed in triplicate. Data are presented as the mean ± SD *p < 0.05, **p < 0.01, ***p < 0.001.