PTBP1 and triple-negative breast carcinoma: We observed that following immunocapture of endogenous PTBP1 by an anti-PTBP1 antibody (but not nonspecific control immunoglobulin G) with Protein G dynabeads, endogenous PTBP1 was able to selectively pull down recombinant MCL1 added to whole-cell lysate from the triple-negative breast cancer cell line MDA-MB-468.