PIANP and neoplasm: After PANP-RAWs were injected through the tail vein of mice, the intratumoral blood vessels could be detected by the ultrasound system at 10, 20, 30, and 40 min, and it was found that PANP-RAWs tended to accumulate at the tumor site in a time-dependent manner; the ultrasound signal could be clearly observed and it was statistically significant (Fig. 5C, D).