PTK7 and Anxiety: CCK + neurons regulate aggression, anxiety, and social defeat responses in rodents (Vasar et al., 1993; Panksepp et al., 2004; Becker et al., 2007; Li et al., 2007), and CCK-4 has been shown to induce panic attacks in humans (Bradwejn et al., 1990; Tõru et al., 2010).