documentclass[]{standalone}
usepackage{tikz}
usepackage{tikz-qtree}
usetikzlibrary{shadows.blur}
usetikzlibrary{calc}

newcommand{propbox}[1]{
    hspace{-.125cm}tikz[baseline=(A.base)]{node[
      fill = red,
      blur shadow={shadow blur steps=5}] (A) {#1};}
}


begin{document}
This is propbox{some} sample text.
end{document}