May be involved in a cell-to cell programmed cell death (PCD) signaling mechanism. Up-regulated by fungal elicitor (PubMed:12833529). Up-regulated in both heat- and senescence-induced programmed cell death (PCD) (PubMed:15276441). Phosphorylated on tyrosine. Identified as a cargo protein of vacuolar sorting receptors (PubMed:23738689). This was based on interactions with truncated vacuolar sorting receptors and their co-secretion in the culture medium (PubMed:23738689). This function is however not supported by recent evidences.