To determine if these regions upregulate p21WAF1/CIP1 and thereby induce growth arrest in ALCL cells, we constructed a panel of retroviral plasmids encoding chimeric receptors which incorporate the extracellular and transmembrane domains of murine 4-1BB alone or in frame with full-length or truncated segments of the human CD30 cytoplasmic tail to enable m4-1BBL-induced CD30 signaling (Figure 2A). Here, TNFRSF8 is linked to anaplastic large cell lymphoma.