FIGURE 4.

Impaired lysosomal degradation contributes to metastasis. Dissected cephalic complexes from third-instar larvae are shown. A–H, RFP was used for labeling tumor clones to distinguish them from the green signal of the GFP-LAMP fusion protein. I–L, Ras^V12 tumor cells were labeled by GFP. In Ras^V12 tumors (A–D), GFP-LAMP fusion proteins were presumably targeted to lysosomes and efficiently degraded. With additional dor⁸ mutation, the lysosomal degradation of GFP-LAMP proteins was blocked inside tumor tissues with invasive potential (E–H). Inhibition of lysosomal degradation by feeding chloroquine (CQ) (J) or monensin (MN) (L) induced VNC invasion of Ras^V12 tumor clones (green) when compared with the control samples (I and K).