Specificity of HOM-MEL-40/SSX2 p103-111 stimulated CD8+ T-cells. The reactivity of T-cells prestimulated with SSX2-derived p103-111 was tested against peptides SSX2 p103-111 (red) and SSX4 p103-111 (green) by ELISPOT. T-cells prestimulated with SSX4 derived p103-111 were tested the same way to exclude any cross-reactivity. The peptides are located at the corresponding positions of the two antigens, which belong to the same cancer testis antigen family. T-cells were derived from a breast cancer patient with an SSX2 and SSX4 positive tumor. Peptide p148-156 derived from human helicase served as a negative control (yellow). T-cells specific for CMV p495-503 were used as a positive control (blue).