Definition: Given an abstract, generate a keyword (a noun phrase) that best describes the focus or contribution of the paper. Such keywords can be directly from the given abstract or outside it.
Input: Abstract: Proliferin (PLF) is a member of the PRL-GH family whose mRNA has been detected in proliferating mouse cells in culture and in mouse placenta. Suspensions of murine placental tissue have been shown to produce PLF detectable by immunoprecipitation. Here we report that PLF is secreted as a heterogeneous glycoprotein by growing mouse cell lines and placental tissue and that the first 29 amino acids of the preprotein serve as a signal peptide. Placental PLF is immunologically distinguishable from the 2 previously described mouse placental lactogens.

Animal