After a 10-day treatment with GCV following tumor formation, the average volume of xenograft tumors developed from C6-sr39TK, C6-TK, or C6 cells were 574.08 ± 107.72, 928.47 ± 165.61, and 1287.24 ± 364.84 mm3, respectively, with a significant difference among these groups (P < 0.05) (Figure 5). Here, TKT is linked to neoplasm.