Extensive research on the nematode "C. elegans" has identified RNA-binding proteins as essential factors during germline and early embryonic development. Their specific function involves the development of somatic tissues (neurons, hypodermis, muscles and excretory cells) as well as providing timing cues for the developmental events. Nevertheless, it is exceptionally challenging to discover the mechanism behind RBPs' function in development due to the difficulty in identifying their RNA targets. This is because most RBPs usually have multiple RNA targets. However, it is indisputable that RBPs exert a critical control in regulating developmental pathways in a concerted manner. In "Drosophila melanogaster", Elav, Sxl and tra-2 are RNA-binding protein encoding genes that are critical in the early sex determination and the maintenance of the somatic sexual state. These genes impose effects on the post-transcriptional level by regulating sex-specific splicing in "Drosophila". Sxl exerts positive regulation of the feminizing gene "tra" to produce a functional tra mRNA in females. In "C. elegans", RNA-binding proteins including FOG-1, MOG-1/-4/-5 and RNP-4 regulate germline and somatic sex determination. Furthermore, several RBPs such as GLD-1, GLD-3, DAZ-1, PGL-1 and OMA-1/-2 exert their regulatory functions during meiotic prophase progression, gametogenesis, and oocyte maturation. In addition to RBPs' functions in germline development, post-transcriptional control also plays a significant role in somatic development. Differing from RBPs that are involved in germline and early embryo development, RBPs functioning in somatic development regulate tissue-specific alternative splicing of the mRNA targets. For instance, MEC-8 and UNC-75 containing RRM domains localize to regions of hypodermis and nervous system, respectively. Furthermore, another RRM-containing RBP, EXC-7, is revealed to localize in embryonic excretory canal cells and throughout the nervous system during somatic development. ZBP1 was shown to regulate dendritogenesis (dendrite formation) in hippocampal neurons. Other RNA-binding proteins involved in dendrite formation are Pumilio and Nanos, FMRP, CPEB and Staufen 1  RBPs are emerging to play a crucial role in tumor development.