Howard Holtzer, professor emeritus of cell and developmental biology (formerly anatomy) in the Perelman School of Medicine, died on November 5 at home at the age of 92.
Dr. Holtzer was born in Brooklyn and served in the US Army during World War II. He received his BS in 1949 and PhD in 1952 at the University of Chicago. Following a postdoctoral fellowship at the College of Physicians and Surgeons, Columbia University, he joined the Penn anatomy faculty in 1953.
While doing research in the lab of Dr. Paul Weiss in Chicago, he did his first extraordinary experiments and made observations that historically are the foundation of much of the molecular work on inductive signals between tissues and how cells communicate during development. Upon joining Penn, he began to apply a new technique, fluorescent labeling of antibodies, to the study of myogenesis. His demonstration of cell lineage commitment as an event that long precedes our ability to recognize the differentiated cell, expanded the frontiers of developmental biology. Other discoveries followed: definitive proof that myoblasts actually fuse with each other to form myotubes; the first demonstration of actin filaments in non-muscle cells; the existence of a new class of filaments, the intermediate filaments (including keratins, lamins and neurofilaments).
After his “official” retirement, he was invited in 1994 to be the Plenary Speaker of a meeting of the Japanese Society for Developmental Biology in Sendai.
Dr. Holtzer is survived by his wife, and longtime collaborator, Dr. Sybil Holtzer.
Contributions may be made to the department of cell and developmental biology, 1157 BRB II/III/6058 benefiting the annual “Howard Holtzer Prize for Research by a Postdoctoral Fellow.”