Fig. 1: CDK4 expression enhances tumor growth in an immune-dependent manner in vivo.

a MCA205 tumor growth curve of C57BL/6 N mice with intratumoral injection of palbociclib (5 mM) or PBS. WT tumor cells (2 × 10⁶/mouse) were transplanted subcutaneously on the right flank of C57BL/6 N mice (n = 5) with palbociclib (5 mM) or PBS treatment at day 6, 7 and 8. b MCA205 tumor growth in nude mice with intratumoral injection of palbociclib (5 mM) or PBS. WT tumor cells (2 × 10⁶/mouse) were transplanted subcutaneously on the right flank of Nu/Nu mice (n = 5) with palbociclib (5 mM) or PBS treatment at day 6, 7 and 8. c Vector and Cdk4^−/− MCA205 tumor growth curve in C57BL/6 N mice (n = 5). d Vector and Cdk4^−/− TC-1 tumor growth curve of in C57BL/6 N mice (n = 5). e Tumor growth curve of vector, Cdk4^−/− and Cdk4-restored MCA205 cells in C57BL/6 N mice (n = 5). f Vector and Cdk4^−/− MCA205 tumor growth curve in nude mice (n = 5). g Vector and Cdk4^−/− TC-1 tumor growth curve in nude mice (n = 5). h, i Tumor growth curve of C57BL/6 N mice re-challenged with WT MCA205. C57BL/6 N mice were first injected with PBS or 1 × 10⁶ Cdk4^−/− MCA205 cells or freeze-thawed WT cells (or PBS as control) on the left flank. The freeze-thaw cycles were conducted for 3 times. Mice (n = 5) were re-challenged with 2 × 10⁶ WT MCA205 cells 14 days later on the right flank. WT MCA205 tumor size on the right flank was monitored. Data are representative of three independent experiments and presented as mean ± SD. Statistical significance was analyzed by the Mann–Whitney U test. ns, no significant, *p < 0.05, **p < 0.01.