SELL and neoplasm: Considering the phenotype of CD8 T cells that had newly entered the tumor, the abundance of TF transcripts such as Tcf7, Klf2, and Lef1, as well as homing molecules such as Sell and Ccr7, in the absence of inhibitory receptor expression (e.g., Pdcd1) and with low levels of Cd44, indicated that CD8T1 likely contained naive CD8 T cells.