CSPG4 and cancer: For the purposes of this review, we recognize CSPG4 as a marker for aggressive, therapy-resistant cancers and are particularly interested in its potential as target for tumor-selective oncolytic agents such as antibody-drug conjugates (ADCs), immunotoxins (ITs) and tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) fusion proteins, described later in this review.