Release of basic fibroblast growth factor, an angiogenic factor devoid of secretory signal sequence: a trivial phenomenon or a novel secretion mechanism?

Basic fibroblast growth factor (bFGF), a potent angiogenesis inducer, lacks a signal sequence. Therefore, it has been proposed that bFGF is primarily released from dead or damaged cells. Other proteins devoid of secretion signals, interleukin 1 beta (IL-1 beta) and the muscle lectin L-14, have been shown to be released via exocytosis, a novel secretion pathway independent of the "classic" endoplasmic reticulum-Golgi route. In the light of these findings and of our own recent results, we discuss evidence that bFGF can be released from single, uninjured cells and mediate functions in an autocrine manner. As is the case for IL-1 beta and L-14, externalization of bFGF may occur via exocytosis, a pathway utilized during development and differentiation.