GPC2 and neuroblastoma: Tian and colleagues screened for potent CARs against neuroblastoma tumor antigens glypican-2 (GPC2 [also called CT3]) and CD276 (also called MGB7H3-LH or B7-H3) using methods to quantify and characterize surface proteins, including digital droplet PCR, pooled competitive optimization of CAR by cellular indexing of transcriptomes and epitopes–sequencing (CITE-sequencing; referred to as P-COCC in Tian et al.), and cytotoxicity assays.