Cys4p advances START both by promoting cell growth and by a separate function, which does not require CBS's catalytic activity.

<p>A, Rate of cell size increase (shown as growth rate, in fl/min) for the indicated strains was measured assuming linear growth from synchronous elutriated cultures in media that contain galactose and induce expression of the <i>P_GAL</i> alleles (see <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1002590#s4" target="_blank">Methods</a>). The average value for each strain is shown with a horizontal bar (± sd). Where indicated, the <i>P</i> values shown were calculated from two-tailed <i>t</i> tests. The data used to calculate the values shown in A and B are in <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1002590#pgen.1002590.s009" target="_blank">Figure S8</a>. B, The critical cell size of the indicated strains (shown in fl), was measured from the same elutriation experiments shown in A (see also <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1002590#pgen.1002590.s010" target="_blank">Figure S9</a>). The analogous experiments in non-inducing, glucose containing, medium are shown in <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1002590#pgen.1002590.s010" target="_blank">Figure S9</a>.