Syk-deficient lymphomas fail to expand in mice. DBL-114 tumor B cells were infected with either pLL3.7-shLuc or pLL3.7-shmSyk and then adoptively transferred into mice. Mice were killed when they developed externally palpable tumors (A). Representative brightfield or fluorescent images of tumor spleens and tumor nodules harvested from mice. (B) Quantitation of percent GFP⁺ cells left in tumors relative to the percentage of GFP⁺ cells transferred into the mice, as determined by FACS analysis of cells before adoptive transfer and after tumor harvest.