AP-1 transcription factor complex mediates rapid proliferation of cord blood CD4⁺ T cells. (A) Line graph showing increased proliferation of cord blood CD4⁺ T cells in response to self-APCs. Cord blood CD4⁺ T-cell proliferation increased with an increasing APC:T-cell ratio of 1:1, 2:1, and 4:1. However, no such effect was observed on peripheral blood CD4⁺ T cells. (B) Line graph showing inhibition of cord blood CD4⁺ T-cell proliferation at different concentrations of AP-1 inhibitor. The inhibitory effect was proportional to the increasing concentration of AP-1 inhibitor. The dots represent mean and error bars represent standard deviation.