“…Herein we discuss some recent findings based on studies of the following selected actin-binding/regulatory proteins in the testis and how these proteins work alone or in concert with others to modulate the organization of actin microfilaments, most notably at the ES to regulate (1) spermatid adhesion and transport and (2) BTB dynamics to facilitate the transport of preleptotene spermatocytes across the immunological barrier. Other regulatory proteins such as actin-bundling proteins plastin 3, Eps8, ezrin, and palladin and regulatory protein kinases (e.g., FAK, c-Src, c-Yes) pertinent to the regulation of spermatogenesis have recently been reviewed [14, 19], and thus, they are not being discussed herein to avoid redundancy. Instead, we focus on a group of actin nucleation proteins; however, these actin nucleation proteins are grouped into two types: one confers branched actin nucleation (e.g., the Arp2/3 complex), whereas the other type confers linear actin nucleation (e.g., formin 1 and Spire 1).…”