PRKCD and neoplasm: We now show, for the first time, that Y374 on PKCδ is phosphorylated by the tyrosine kinase FER and that the resultant pY374-PKCδ compromises early to late endosome maturation and consequently impairs degradation of RTKs, thereby promoting recycling back to the cell surface to increase signaling and anchorage-independent cell growth, a surrogate measure for tumor-forming potential.