private String getTitleString() {
		switch(currentLevel) {
		case 1: return "APC"; 
		case 2: return "S-Cdk"; 
		case 3: return "p53"; 
		case 4: return "Delta-Notch"; 
		case 5: return "TGF-Beta"; 
		case 6: return "Hedgehog"; 
		case 7: return "Wnt"; 
		}
		return "";
	}