Gerry Baker is Editor at Large of The Wall Street Journal. His weekly column for the editorial page, “Free Expression,” appears in The Wall Street Journal each Tuesday. Mr. Baker is also host ...

Expression systems are genetic constructs (a gene encoded by DNA) that are designed to produce a protein, or an RNA (ribonucleic acid), either inside or outside a cell. Expression systems are used ...

Many perturbations affect only a subset of cells, while the rest remain largely unaffected. Existing single-cell analysis methods may fail to isolate the affected cells and their markers.